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  • C#/.NET Little Wonders: The EventHandler and EventHandler&lt;TEventArgs&gt; delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last two weeks, we examined the Action family of delegates (and delegates in general), and the Func family of delegates and how they can be used to support generic, reusable algorithms and classes. So this week, we are going to look at a handy pair of delegates that can be used to eliminate the need for defining custom delegates when creating events: the EventHandler and EventHandler<TEventArgs> delegates. Events and delegates Before we begin, let’s quickly consider events in .NET.  According to the MSDN: An event in C# is a way for a class to provide notifications to clients of that class when some interesting thing happens to an object. So, basically, you can create an event in a type so that users of that type can subscribe to notifications of things of interest.  How is this different than some of the delegate programming that we talked about in the last two weeks?  Well, you can think of an event as a special access modifier on a delegate.  Some differences between the two are: Events are a special access case of delegates They behave much like delegates instances inside the type they are declared in, but outside of that type they can only be (un)subscribed to. Events can specify add/remove behavior explicitly If you want to do additional work when someone subscribes or unsubscribes to an event, you can specify the add and remove actions explicitly. Events have access modifiers, but these only specify the access level of those who can (un)subscribe A public event, for example, means anyone can (un)subscribe, but it does not mean that anyone can raise (invoke) the event directly.  Events can only be raised by the type that contains them In contrast, if a delegate is visible, it can be invoked outside of the object (not even in a sub-class!). Events tend to be for notifications only, and should be treated as optional Semantically speaking, events typically don’t perform work on the the class directly, but tend to just notify subscribers when something of note occurs. My basic rule-of-thumb is that if you are just wanting to notify any listeners (who may or may not care) that something has happened, use an event.  However, if you want the caller to provide some function to perform to direct the class about how it should perform work, make it a delegate. Declaring events using custom delegates To declare an event in a type, we simply use the event keyword and specify its delegate type.  For example, let’s say you wanted to create a new TimeOfDayTimer that triggers at a given time of the day (as opposed to on an interval).  We could write something like this: 1: public delegate void TimeOfDayHandler(object source, ElapsedEventArgs e); 2:  3: // A timer that will fire at time of day each day. 4: public class TimeOfDayTimer : IDisposable 5: { 6: // Event that is triggered at time of day. 7: public event TimeOfDayHandler Elapsed; 8:  9: // ... 10: } The first thing to note is that the event is a delegate type, which tells us what types of methods may subscribe to it.  The second thing to note is the signature of the event handler delegate, according to the MSDN: The standard signature of an event handler delegate defines a method that does not return a value, whose first parameter is of type Object and refers to the instance that raises the event, and whose second parameter is derived from type EventArgs and holds the event data. If the event does not generate event data, the second parameter is simply an instance of EventArgs. Otherwise, the second parameter is a custom type derived from EventArgs and supplies any fields or properties needed to hold the event data. So, in a nutshell, the event handler delegates should return void and take two parameters: An object reference to the object that raised the event. An EventArgs (or a subclass of EventArgs) reference to event specific information. Even if your event has no additional information to provide, you are still expected to provide an EventArgs instance.  In this case, feel free to pass the EventArgs.Empty singleton instead of creating new instances of EventArgs (to avoid generating unneeded memory garbage). The EventHandler delegate Because many events have no additional information to pass, and thus do not require custom EventArgs, the signature of the delegates for subscribing to these events is typically: 1: // always takes an object and an EventArgs reference 2: public delegate void EventHandler(object sender, EventArgs e) It would be insane to recreate this delegate for every class that had a basic event with no additional event data, so there already exists a delegate for you called EventHandler that has this very definition!  Feel free to use it to define any events which supply no additional event information: 1: public class Cache 2: { 3: // event that is raised whenever the cache performs a cleanup 4: public event EventHandler OnCleanup; 5:  6: // ... 7: } This will handle any event with the standard EventArgs (no additional information).  But what of events that do need to supply additional information?  Does that mean we’re out of luck for subclasses of EventArgs?  That’s where the generic for of EventHandler comes into play… The generic EventHandler<TEventArgs> delegate Starting with the introduction of generics in .NET 2.0, we have a generic delegate called EventHandler<TEventArgs>.  Its signature is as follows: 1: public delegate void EventHandler<TEventArgs>(object sender, TEventArgs e) 2: where TEventArgs : EventArgs This is similar to EventHandler except it has been made generic to support the more general case.  Thus, it will work for any delegate where the first argument is an object (the sender) and the second argument is a class derived from EventArgs (the event data). For example, let’s say we wanted to create a message receiver, and we wanted it to have a few events such as OnConnected that will tell us when a connection is established (probably with no additional information) and OnMessageReceived that will tell us when a new message arrives (probably with a string for the new message text). So for OnMessageReceived, our MessageReceivedEventArgs might look like this: 1: public sealed class MessageReceivedEventArgs : EventArgs 2: { 3: public string Message { get; set; } 4: } And since OnConnected needs no event argument type defined, our class might look something like this: 1: public class MessageReceiver 2: { 3: // event that is called when the receiver connects with sender 4: public event EventHandler OnConnected; 5:  6: // event that is called when a new message is received. 7: public event EventHandler<MessageReceivedEventArgs> OnMessageReceived; 8:  9: // ... 10: } Notice, nowhere did we have to define a delegate to fit our event definition, the EventHandler and generic EventHandler<TEventArgs> delegates fit almost anything we’d need to do with events. Sidebar: Thread-safety and raising an event When the time comes to raise an event, we should always check to make sure there are subscribers, and then only raise the event if anyone is subscribed.  This is important because if no one is subscribed to the event, then the instance will be null and we will get a NullReferenceException if we attempt to raise the event. 1: // This protects against NullReferenceException... or does it? 2: if (OnMessageReceived != null) 3: { 4: OnMessageReceived(this, new MessageReceivedEventArgs(aMessage)); 5: } The above code seems to handle the null reference if no one is subscribed, but there’s a problem if this is being used in multi-threaded environments.  For example, assume we have thread A which is about to raise the event, and it checks and clears the null check and is about to raise the event.  However, before it can do that thread B unsubscribes to the event, which sets the delegate to null.  Now, when thread A attempts to raise the event, this causes the NullReferenceException that we were hoping to avoid! To counter this, the simplest best-practice method is to copy the event (just a multicast delegate) to a temporary local variable just before we raise it.  Since we are inside the class where this event is being raised, we can copy it to a local variable like this, and it will protect us from multi-threading since multicast delegates are immutable and assignments are atomic: 1: // always make copy of the event multi-cast delegate before checking 2: // for null to avoid race-condition between the null-check and raising it. 3: var handler = OnMessageReceived; 4: 5: if (handler != null) 6: { 7: handler(this, new MessageReceivedEventArgs(aMessage)); 8: } The very slight trade-off is that it’s possible a class may get an event after it unsubscribes in a multi-threaded environment, but this is a small risk and classes should be prepared for this possibility anyway.  For a more detailed discussion on this, check out this excellent Eric Lippert blog post on Events and Races. Summary Generic delegates give us a lot of power to make generic algorithms and classes, and the EventHandler delegate family gives us the flexibility to create events easily, without needing to redefine delegates over and over.  Use them whenever you need to define events with or without specialized EventArgs.   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Delegates, EventHandler

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  • CodePlex Daily Summary for Thursday, March 25, 2010

    CodePlex Daily Summary for Thursday, March 25, 2010New ProjectsAccessibilityChecker: Accessibility Checker is custom feature developed to check accessibility requirements in a SharePoint PortalAnne Epstein - Personal Repository: Project Description This project contains multiple samples with various snippets and projects from blog posts, user group talks, and conference se...BatterySaver: BatterySaver is a simple application, in C#, that allows laptop users to perform actions based on battery notification events (switching from batte...dtxJson: C# coded JSON (JavaScript Object Notation) parser.eCamp: eCamp is a modular and extensible electronic camp management application. Written in C# and WPF, it follows many of the latest technology trends su...epdevplatform: epdevplatformERP: Environment Colaborative Resources ProjectFaceLight - Simple Silverlight Face Detection: FaceLight is a simple facial recognition method that can be used with Silverlight 's webcam. It searches for a certain sized skin color region in a...Forum PAF - The Open Source .Net Forum - From Viet Nam - By Thomas John (jntpaf): The Open Source .Net Forum - From Viet Nam ------------------------- Các phần mềm cần thiết để chạy Forum PAF: 1. .Net Framework 2.0 (trở lên) 2....Gawam Savel - Sistema de Avaliação Eletrônica: Projeto de TCC ...Html5 Helpers and tools for Asp.Net MVC: Html5 Helper aims to provide a generic helper context to produce HTML5 content in ASP.NET MVCIfeanyi Echeruo's WPF Recipes: WPF Recipes C# code samples showing how to solve some non-trivial problems in WPFITM 495 - iPhone App: school project iphone appKnowledge Exchange: Stack Overflow Inspired Knowledge ExchangeMailCheck: Mail检查程序。NetBoard: NetBoard is a lightweight system designed to act as the Blackboard in a micro-blackboard architecture for use within an OO system - even when withi...RodBass.com: RodBass.comsemanticrest: This is a vision of semantics mashups for rest web services.StatSpaceUI: StatSpaceUITFS Merge Tool: A small tool for merging changesets between TFS branches.The Interface To End All Interfaces: We interfaced everything, so that you can implement anything...Tim - Open Source Projects And Samples: Open source projects / Samples for http://tim.bellette.netWindows XNA: A place for those who enjoy there XNA Game Studio programing on Windows. For a place to share XNA Game Studio games for Windows in English. I'm loo...XAML Code Snippets addin for Visual Studio 2010: Provides support for adding XAML code snippets in the Visual Studio 2010 code editor for XAML in WPF and Silverlight projects.New ReleasesAnyWorks: AnyWorks1.2Bin: AnyWorks1.2AnyWorks: AnyWorks1.2Src: AnyWorks1.2AppFabric Caching Admin Tool: AppFabric Caching Admin Tool 1.0: System Requirements:.NET 4.0 RC AppFabric Caching Beta2 Test On:Win 7 (64x) Note: Must run as Administrator !!!ASP.NET Wiki Control: Release 1.1: - Modified text and varchar columns to nvarchar for unicode support. - Modified path info logic to disable its use if the page's raw url currently...B&W Port Scanner: Black`n`White Port Scanner 2.0: Fast Cross-Platform Port Scanner with Vulnerability Detection Tools. 3 vulnerability detection tools are included in this version: - Detection of ...BatterySaver: 0.1: Initial Release This is the initial release of the application. The application is very much beta with lots of changes upcoming. Known Issues The...BatterySaver: 0.2: Changes+ Add support for enabling and disabling devices (6)Compare .NET Objects: Version 1.2.0.0: New Features: Compare Generic Classes that Implement IList Indexers Compare Datasets Compare DataTables Compare DataRows Consider IList and...Controlled Vocabulary: 1.0.0.3: System Requirements Outlook 2007 / 2010 .Net Framework 3.5 Installation 1. Close Outlook (Use Task Manager to ensure no running instances in the b...crudwork is a library of reuseable classes for developing .NET applications: crudwork 2.2.0.2: minor changes. new guid for msi and new strongly named guidDigitallyCreated Utilities: DigitallyCreated Utilities v1.0.0: This release is the v1.0.0 version of DigitallyCreated Utilities. Binary Distribution The binary distribution contains the following: Compiled bin...DirectQ: Release 1.8.2: Adds several bugfixes and improved functionality. This release supersedes 1.8.1 which will be shortly removed. A very big THANK YOU to everyone w...DotNetNuke® Community Edition: 05.03.01: Major Highlights Issue fixed issue with the email notifications where the From and To addresses were swapped. Issue fixed with signature ch...Encrypted Notes: Encrypted Notes 1.5: This is the latest version of Encrypted Notes (1.5). It has an installer - it will create a directory 'CPascoe' in My Documents. Once you have ext...EnhSim: Release v1.9.8.1: Release v1.9.8.1Adding in the Glyph of Flame Shock changes in 3.3.3FlickrNet API Library: 3.0 Beta: A brand new version of the FlickrNet library, exposing 100% of the Flickr API's methods, along with streamlined class and method names. All classe...Forum PAF - The Open Source .Net Forum - From Viet Nam - By Thomas John (jntpaf): Forum PAF - The Open Source .Net Forum: A, Các phần mềm cần thiết để chạy Forum PAF: 1. .Net Framework 2.0 (trở lên) 2. Ajax Extension 1.0 (trở lên) 3. Sql Server 2005 (Sql Server Expr...HydroDesktop - CUAHSI Hydrologic Information System Desktop Application: HydroDesktop 0.7.3735 Alpha Installer: This is the testing release of the HydroDesktop 0.7 alpha version. Features supported in this version include: Search for data and download of Hydr...MDownloader: MDownloader-0.15.9.56953: Fixed Uploading.com links detection.MiniTwitter: 1.10: MiniTwitter 1.10 更新内容 追加 未読管理時に未読数をタブに表示する機能を実装 サイレントモードを実装(通知領域アイコンを右クリックして出るメニューから切り替え) 修正 「お気に入りワードを含む項目だけ表示する」オプションが機能していなかった問題を修正NoteExpress User Tools (NEUT) - Do it by ourselves!: NoteExpress User Tools 1.9.1: 测试版本:NoteExpress 2.5.0.1147 #修正一个改动的bugOneCMS: OneCMS 2.6: OneCMS 2.6 is finally here! Along with various bug fixes 2.6 also brings with it many new features such as the videos module, plugins system, and m...Quantity System Framework: Quantity System Calculator 1.1.9.93: Experience the new edition of the quantity system with text support and function treated as values now you can multiply functions and divide funct...Selection Maker: Selection Maker 1.4: some minor bugs fixed. icon added for running and uninstalling the application.sPATCH: sPatcher v0.8a: + Disabled patchers proxy settings to increase connection speed sPatch - Server Example *Contains a sample Patch that "downgrades" PWI 1.4.2 Clien...VSTT 2008 Quick Reference Guide: VS Performance Testing Quick Reference V2.0: Visual Studio Performance Testing Quick Reference Guide (Version 2.0)WeatherBar: WeatherBar 2.0: WeatherBar 2.0 Changelog: Introduced application settings. Modified UI. Ability to switch between Fahrenheit and Celsius (application-wide). ...WillStrohl.LightboxGallery Module for DotNetNuke: WillStrohl.LightboxGallery v1.02.01: This version of the Lightbox Gallery Module adds the following features: Upgraded the Autocomplete jQuery plugin Fixed an IE8 error that was occu...Windows XNA: Base Defense Alpha 0.339: Alpha 0.338 had a really bad bug that made the game crash, that is what I get for coding after 3am... I also made some AI for the Raptor. So now it...WPF Dynamic Data Display: Silverlight DynamicDataDisplay v0.2 - Spring 2010: Silverlight version of WPF DynamicDataDisplay charting library The version 0.2 shows a greater performance comparing with version 0.1 while having...Most Popular ProjectsMetaSharpRawrWBFS ManagerASP.NET Ajax LibrarySilverlight ToolkitMicrosoft SQL Server Product Samples: DatabaseAJAX Control ToolkitLiveUpload to FacebookWindows Presentation Foundation (WPF)ASP.NETMost Active ProjectsRawrjQuery Library for SharePoint Web ServicesFarseer Physics EngineBlogEngine.NETFacebook Developer ToolkitNB_Store - Free DotNetNuke Ecommerce Catalog ModulePHPExcelTable2ClassFluent Ribbon Control SuiteLINQ to Twitter

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  • CodePlex Daily Summary for Sunday, November 11, 2012

    CodePlex Daily Summary for Sunday, November 11, 2012Popular ReleasesZXMAK2: Version 2.7.2.0: show extended rzx error info fix reset lag for PROFI ULA 5.xx fix reset behavior fix PROFI ULA timings (thanks to solegstar) fix #FF port for PROFI ULA add ATM710 memory module add new predefined machine configs: ATM Turbo 2, PROFI 3.XX???????: Monitor 2012-11-11: This is the first releaseVidCoder: 1.4.5 Beta: Removed the old Advanced user interface and moved x264 preset/profile/tune there instead. The functionality is still available through editing the options string. Added ability to specify the H.264 level. Added ability to choose VidCoder's interface language. If you are interested in translating, we can get VidCoder in your language! Updated WPF text rendering to use the better Display mode. Updated HandBrake core to SVN 5045. Removed logic that forced the .m4v extension in certain ...ImageGlass: Version 1.5: http://i1214.photobucket.com/albums/cc483/phapsuxeko/ImageGlass/1.png v1.5.4401.3015 Thumbnail bar: Increase loading speed Thumbnail image with ratio Support personal customization: mouse up, mouse down, mouse hover, selected item... Scroll to show all items Image viewer Zoom by scroll, or selected rectangle Speed up loading Zoom to cursor point New background design and customization and others... v1.5.4430.483 Thumbnail bar: Auto move scroll bar to selected image Show / Hi...Building Windows 8 Apps with C# and XAML: Full Source Chapters 1 - 10 for Windows 8 Fix 002: This is the full source from all chapters of the book, compiled and tested on Windows 8 RTM. Includes: A fix for the Netflix example from Chapter 6 that was missing a service reference A fix for the ImageHelper issue (images were not being saved) - this was due to the buffer being inadequate and required streaming the writeable bitmap to a buffer first before encoding and savingmyCollections: Version 2.3.2.0: New in this version : Added TheGamesDB.net API for Games and NDS Added Support for Windows Media Center Added Support for myMovies Added Support for XBMC Added Support for Dune HD Added Support for Mede8er Added Support for WD HDTV Added Fast search options Added order by Artist/Album for music You can now create covers and background for games You can now update your ID3 tag with the info of myCollections Fixed several provider Performance improvement New Splash ...Draw: Draw 1.0: Drawing PadPlayer Framework by Microsoft: Player Framework for Windows 8 (v1.0): IMPORTANT: List of breaking changes from preview 7 Ability to move control panel or individual elements outside media player. more info... New Entertainment app theme for out of the box support for Windows 8 Entertainment app guidelines. more info... VSIX reference names shortened. Allows seeing plugin name from "Add Reference" dialog without resizing. FreeWheel SmartXML now supports new "Standard" event callback type. Other minor misc fixes and improvements ADDITIONAL DOWNLOADSSmo...WebSearch.Net: WebSearch.Net 3.1: WebSearch.Net is an open-source research platform that provides uniform data source access, data modeling, feature calculation, data mining, etc. It facilitates the experiments of web search researchers due to its high flexibility and extensibility. The platform can be used or extended by any language compatible for .Net 2 framework, from C# (recommended), VB.Net to C++ and Java. Thanks to the large coverage of knowledge in web search research, it is necessary to model the techniques and main...Umbraco CMS: Umbraco 4.10.0: NugetNuGet BlogRead the release blog post for 4.10.0. Whats newMVC support New request pipeline Many, many bugfixes (see the issue tracker for a complete list) Read the documentation for the MVC bits. Breaking changesWe have done all we can not to break backwards compatibility, but we had to do some minor breaking changes: Removed graphicHeadlineFormat config setting from umbracoSettings.config (an old relic from the 3.x days) U4-690 DynamicNode ChildrenAsList was fixed, altering it'...SQL Server Partitioned Table Framework: Partitioned Table Framework Release 1.0: SQL Server 2012 ReleaseSharePoint Manager 2013: SharePoint Manager 2013 Release ver 1.0.12.1106: SharePoint Manager 2013 Release (ver: 1.0.12.1106) is now ready for SharePoint 2013. The new version has an expanded view of the SharePoint object model and has been tested on SharePoint 2013 RTM. As a bonus, the new version is also available for SharePoint 2010 as a separate download.D3D9Client: D3D9Client R7: New release for Orbiter 2010-P1 - Added horizon/sun angle for night-lights into the configuration file (default 10deg) - Some runway lights related bugs are fixed - Added more configuration options for runway lightsFiskalizacija za developere: FiskalizacijaDev 1.2: Verzija 1.2. je, prije svega, odgovor na novu verziju Tehnicke specifikacije (v1.1.) koja je objavljena prije nekoliko dana. Pored novosti vezanih uz (sitne) izmjene u spomenutoj novoj verziji Tehnicke dokumentacije, projekt smo prošili sa nekim dodatnim feature-ima od kojih je vecina proizašla iz vaših prijedloga - hvala :) Novosti u v1.2. su: - Neusuglašenost zahtjeva (http://fiskalizacija.codeplex.com/workitem/645) - Sample projekt - iznosi se množe sa 100 (http://fiskalizacija.codeplex.c...MFCMAPI: October 2012 Release: Build: 15.0.0.1036 Full release notes at SGriffin's blog. If you just want to run the MFCMAPI or MrMAPI, get the executables. If you want to debug them, get the symbol files and the source. The 64 bit builds will only work on a machine with Outlook 2010 64 bit installed. All other machines should use the 32 bit builds, regardless of the operating system. Facebook BadgeDictationTool: DictationCool-WPF: • Open a media file to start a new dication. • Open a dct file to continue a dictation. • Compare your dictation with original text if exists. • Save your dictation to dct file, and restore it to continue later. • Save the compared result to html file.MCEBuddy 2.x: MCEBuddy 2.3.7: Changelog for 2.3.7 (32bit and 64bit) 1. Improved performance of MP4 Fast and M4V Fast Profiles (no deinterlacing, removed --decomb) 2. Improved priority handling 3. Added support for Pausing and Resume conversions 4. Added support for fallback to source directory if network destination directory is unavailable 5. MCEBuddy now installs ShowAnalyzer during installation 6. Added support for long description atom in iTunesDyanamic Reports (RDLC) - SharePoint 2010 Visual WebPart: Initial Release: This is a Initial Release.HTML Renderer: HTML Renderer 1.0.0.0 (3): Major performance improvement (http://theartofdev.wordpress.com/2012/10/25/how-i-optimized-html-renderer-and-fell-in-love-with-vs-profiler/) Minor fixes raised in issue tracker and discussions.Window Manager: Window Manager 1.0: First releaseNew Projectsarteytex: este es una prueba blockworld: An implementation of a goal stack planner.Customer Note: customer note is windows store applicationDraw: ?????????????:??????、CAD??、????。Football Management: Football Management System is web management system for football (soccer) leagues, teams and players. Hijri Converter API: This project is aimed to create a simple RESTful API using VB and ASP.NET to do Hijri-to-Gregorian and Gregorian-to-Hijri conversion.httpclient?????????: httpclient?????????(1)??????????(2)?????????(3)??2012-11-06??,???????。 Imagine Cup 2013: Develop project to Imagine Cup 2013MyAppReji: MyAppN2F Request: The N2F Request object is used to handle interactions between N2F and the global $_REQUEST variable, sanitizing any results which are returned.Orchard Metro Theme: Orchard Metro Theme is a clean and flexible multi-zone theme.Poker Clock And Goodies: poker w8ProjectASPReviewer: Review website for notebooks, tablets and smartphones.Prototype: Its about making an proto type for the final project.Prototype - 7COM0207: 7COM0207 web scripting module, Assignment 2QuickToAD: QuickToAD is a foundational development project for the purpose of jump-starting data-driven application projects.Release Manager: Release Manager is a project to design and develop Windows based Release Management Software.ResW File Code Generator: A Visual Studio 2012 Custom Tool for generating a strongly typed helper class for accessing localized resources from a .ResW file.SEO Tools: This is a website containing some commonly used SEO tools. I have only added a blog ping utility at this time but there is more to come. Thales communicator: A C# library that helps communicate with Thales HSMTrivial: A trivia framework: Trivial is a C# framework that helps you creating custom trivia-like applications.

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  • Routing to a Controller with no View in Angular

    - by Rick Strahl
    I've finally had some time to put Angular to use this week in a small project I'm working on for fun. Angular's routing is great and makes it real easy to map URL routes to controllers and model data into views. But what if you don't actually need a view, if you effectively need a headless controller that just runs code, but doesn't render a view?Preserve the ViewWhen Angular navigates a route and and presents a new view, it loads the controller and then renders the view from scratch. Views are not cached or stored, but displayed and then removed. So if you have routes configured like this:'use strict'; // Declare app level module which depends on filters, and services window.myApp = angular.module('myApp', ['myApp.filters', 'myApp.services', 'myApp.directives', 'myApp.controllers']). config(['$routeProvider', function($routeProvider) { $routeProvider.when('/map', { template: "partials/map.html ", controller: 'mapController', reloadOnSearch: false, animation: 'slide' }); … $routeProvider.otherwise({redirectTo: '/map'}); }]); Angular routes to the mapController and then re-renders the map.html template with the new data from the $scope filled in.But, but… I don't want a new View!Now in most cases this works just fine. If I'm rendering plain DOM content, or textboxes in a form interface that is all fine and dandy - it's perfectly fine to completely re-render the UI.But in some cases, the UI that's being managed has state and shouldn't be redrawn. In this case the main page in question has a Google Map on it. The map is  going to be manipulated throughout the lifetime of the application and the rest of the pages. In my application I have a toolbar on the bottom and the rest of the content is replaced/switched out by the Angular Views:The problem is that the map shouldn't be redrawn each time the Location view is activated. It should maintain its state, such as the current position selected (which can move), and shouldn't redraw due to the overhead of re-rendering the initial map.Originally I set up the map, exactly like all my other views - as a partial, that is rendered with a separate file, but that didn't work.The Workaround - Controller Only RoutesThe workaround for this goes decidedly against Angular's way of doing things:Setting up a Template-less RouteIn-lining the map view directly into the main pageHiding and showing the map view manuallyLet's see how this works.Controller Only RouteThe template-less route is basically a route that doesn't have any template to render. This is not directly supported by Angular, but thankfully easy to fake. The end goal here is that I want to simply have the Controller fire and then have the controller manage the display of the already active view by hiding and showing the map and any other view content, in effect bypassing Angular's view display management.In short - I want a controller action, but no view rendering.The controller-only or template-less route looks like this: $routeProvider.when('/map', { template: " ", // just fire controller controller: 'mapController', animation: 'slide' });Notice I'm using the template property rather than templateUrl (used in the first example above), which allows specifying a string template, and leaving it blank. The template property basically allows you to provide a templated string using Angular's HandleBar like binding syntax which can be useful at times. You can use plain strings or strings with template code in the template, or as I'm doing here a blank string to essentially fake 'just clear the view'. In-lined ViewSo if there's no view where does the HTML go? Because I don't want Angular to manage the view the map markup is in-lined directly into the page. So instead of rendering the map into the Angular view container, the content is simply set up as inline HTML to display as a sibling to the view container.<div id="MapContent" data-icon="LocationIcon" ng-controller="mapController" style="display:none"> <div class="headerbar"> <div class="right-header" style="float:right"> <a id="btnShowSaveLocationDialog" class="iconbutton btn btn-sm" href="#/saveLocation" style="margin-right: 2px;"> <i class="icon-ok icon-2x" style="color: lightgreen; "></i> Save Location </a> </div> <div class="left-header">GeoCrumbs</div> </div> <div class="clearfix"></div> <div id="Message"> <i id="MessageIcon"></i> <span id="MessageText"></span> </div> <div id="Map" class="content-area"> </div> </div> <div id="ViewPlaceholder" ng-view></div>Note that there's the #MapContent element and the #ViewPlaceHolder. The #MapContent is my static map view that is always 'live' and is initially hidden. It is initially hidden and doesn't get made visible until the MapController controller activates it which does the initial rendering of the map. After that the element is persisted with the map data already loaded and any future access only updates the map with new locations/pins etc.Note that default route is assigned to the mapController, which means that the mapController is fired right as the page loads, which is actually a good thing in this case, as the map is the cornerstone of this app that is manipulated by some of the other controllers/views.The Controller handles some UISince there's effectively no view activation with the template-less route, the controller unfortunately has to take over some UI interaction directly. Specifically it has to swap the hidden state between the map and any of the other views.Here's what the controller looks like:myApp.controller('mapController', ["$scope", "$routeParams", "locationData", function($scope, $routeParams, locationData) { $scope.locationData = locationData.location; $scope.locationHistory = locationData.locationHistory; if ($routeParams.mode == "currentLocation") { bc.getCurrentLocation(false); } bc.showMap(false,"#LocationIcon"); }]);bc.showMap is responsible for a couple of display tasks that hide/show the views/map and for activating/deactivating icons. The code looks like this:this.showMap = function (hide,selActiveIcon) { if (!hide) $("#MapContent").show(); else { $("#MapContent").hide(); } self.fitContent(); if (selActiveIcon) { $(".iconbutton").removeClass("active"); $(selActiveIcon).addClass("active"); } };Each of the other controllers in the app also call this function when they are activated to basically hide the map and make the View Content area visible. The map controller makes the map.This is UI code and calling this sort of thing from controllers is generally not recommended, but I couldn't figure out a way using directives to make this work any more easily than this. It'd be easy to hide and show the map and view container using a flag an ng-show, but it gets tricky because of scoping of the $scope. I would have to resort to storing this setting on the $rootscope which I try to avoid. The same issues exists with the icons.It sure would be nice if Angular had a way to explicitly specify that a View shouldn't be destroyed when another view is activated, so currently this workaround is required. Searching around, I saw a number of whacky hacks to get around this, but this solution I'm using here seems much easier than any of that I could dig up even if it doesn't quite fit the 'Angular way'.Angular nice, until it's notOverall I really like Angular and the way it works although it took me a bit of time to get my head around how all the pieces fit together. Once I got the idea how the app/routes, the controllers and views snap together, putting together Angular pages becomes fairly straightforward. You can get quite a bit done never going beyond those basics. For most common things Angular's default routing and view presentation works very well.But, when you do something a bit more complex, where there are multiple dependencies or as in this case where Angular doesn't appear to support a feature that's absolutely necessary, you're on your own. Finding information on more advanced topics is not trivial especially since versions are changing so rapidly and the low level behaviors are changing frequently so finding something that works is often an exercise in trial and error. Not that this is surprising. Angular is a complex piece of kit as are all the frameworks that try to hack JavaScript into submission to do something that it was really never designed to. After all everything about a framework like Angular is an elaborate hack. A lot of shit has to happen to make this all work together and at that Angular (and Ember, Durandel etc.) are pretty amazing pieces of JavaScript code. So no harm, no foul, but I just can't help feeling like working in toy sandbox at times :-)© Rick Strahl, West Wind Technologies, 2005-2013Posted in Angular  JavaScript   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Residual packages Ubuntu 12.04

    - by hydroxide
    I have an Asus Q500A with win8 and Ubuntu 12.04 64 bit; Linux kernel 3.8.0-32-generic. I have been having residual package issues which have been giving me trouble trying to reconfigure xserver-xorg-lts-raring. I tried removing all residual packages from synaptic but the following were not removed. Output of sudo dpkg -l | grep "^rc" rc gstreamer0.10-plugins-good:i386 0.10.31-1ubuntu1.2 GStreamer plugins from the "good" set rc libaa1:i386 1.4p5-39ubuntu1 ASCII art library rc libaio1:i386 0.3.109-2ubuntu1 Linux kernel AIO access library - shared library rc libao4:i386 1.1.0-1ubuntu2 Cross Platform Audio Output Library rc libasn1-8-heimdal:i386 1.6~git20120311.dfsg.1-2ubuntu0.1 Heimdal Kerberos - ASN.1 library rc libasound2:i386 1.0.25-1ubuntu10.2 shared library for ALSA applications rc libasyncns0:i386 0.8-4 Asynchronous name service query library rc libatk1.0-0:i386 2.4.0-0ubuntu1 ATK accessibility toolkit rc libavahi-client3:i386 0.6.30-5ubuntu2 Avahi client library rc libavahi-common3:i386 0.6.30-5ubuntu2 Avahi common library rc libavc1394-0:i386 0.5.3-1ubuntu2 control IEEE 1394 audio/video devices rc libcaca0:i386 0.99.beta17-2.1ubuntu2 colour ASCII art library rc libcairo-gobject2:i386 1.10.2-6.1ubuntu3 The Cairo 2D vector graphics library (GObject library) rc libcairo2:i386 1.10.2-6.1ubuntu3 The Cairo 2D vector graphics library rc libcanberra-gtk0:i386 0.28-3ubuntu3 GTK+ helper for playing widget event sounds with libcanberra rc libcanberra0:i386 0.28-3ubuntu3 simple abstract interface for playing event sounds rc libcap2:i386 1:2.22-1ubuntu3 support for getting/setting POSIX.1e capabilities rc libcdparanoia0:i386 3.10.2+debian-10ubuntu1 audio extraction tool for sampling CDs (library) rc libcroco3:i386 0.6.5-1ubuntu0.1 Cascading Style Sheet (CSS) parsing and manipulation toolkit rc libcups2:i386 1.5.3-0ubuntu8 Common UNIX Printing System(tm) - Core library rc libcupsimage2:i386 1.5.3-0ubuntu8 Common UNIX Printing System(tm) - Raster image library rc libcurl3:i386 7.22.0-3ubuntu4.3 Multi-protocol file transfer library (OpenSSL) rc libdatrie1:i386 0.2.5-3 Double-array trie library rc libdbus-glib-1-2:i386 0.98-1ubuntu1.1 simple interprocess messaging system (GLib-based shared library) rc libdbusmenu-qt2:i386 0.9.2-0ubuntu1 Qt implementation of the DBusMenu protocol rc libdrm-nouveau2:i386 2.4.43-0ubuntu0.0.3 Userspace interface to nouveau-specific kernel DRM services -- runtime rc libdv4:i386 1.0.0-3ubuntu1 software library for DV format digital video (runtime lib) rc libesd0:i386 0.2.41-10build3 Enlightened Sound Daemon - Shared libraries rc libexif12:i386 0.6.20-2ubuntu0.1 library to parse EXIF files rc libexpat1:i386 2.0.1-7.2ubuntu1.1 XML parsing C library - runtime library rc libflac8:i386 1.2.1-6 Free Lossless Audio Codec - runtime C library rc libfontconfig1:i386 2.8.0-3ubuntu9.1 generic font configuration library - runtime rc libfreetype6:i386 2.4.8-1ubuntu2.1 FreeType 2 font engine, shared library files rc libgail18:i386 2.24.10-0ubuntu6 GNOME Accessibility Implementation Library -- shared libraries rc libgconf-2-4:i386 3.2.5-0ubuntu2 GNOME configuration database system (shared libraries) rc libgcrypt11:i386 1.5.0-3ubuntu0.2 LGPL Crypto library - runtime library rc libgd2-xpm:i386 2.0.36~rc1~dfsg-6ubuntu2 GD Graphics Library version 2 rc libgdbm3:i386 1.8.3-10 GNU dbm database routines (runtime version) rc libgdk-pixbuf2.0-0:i386 2.26.1-1 GDK Pixbuf library rc libgif4:i386 4.1.6-9ubuntu1 library for GIF images (library) rc libgl1-mesa-dri-lts-quantal:i386 9.0.3-0ubuntu0.4~precise1 free implementation of the OpenGL API -- DRI modules rc libgl1-mesa-dri-lts-raring:i386 9.1.4-0ubuntu0.1~precise2 free implementation of the OpenGL API -- DRI modules rc libgl1-mesa-glx:i386 8.0.4-0ubuntu0.6 free implementation of the OpenGL API -- GLX runtime rc libgl1-mesa-glx-lts-quantal:i386 9.0.3-0ubuntu0.4~precise1 free implementation of the OpenGL API -- GLX runtime rc libgl1-mesa-glx-lts-raring:i386 9.1.4-0ubuntu0.1~precise2 free implementation of the OpenGL API -- GLX runtime rc libglapi-mesa:i386 8.0.4-0ubuntu0.6 free implementation of the GL API -- shared library rc libglapi-mesa-lts-quantal:i386 9.0.3-0ubuntu0.4~precise1 free implementation of the GL API -- shared library rc libglapi-mesa-lts-raring:i386 9.1.4-0ubuntu0.1~precise2 free implementation of the GL API -- shared library rc libglu1-mesa:i386 8.0.4-0ubuntu0.6 Mesa OpenGL utility library (GLU) rc libgnome-keyring0:i386 3.2.2-2 GNOME keyring services library rc libgnutls26:i386 2.12.14-5ubuntu3.5 GNU TLS library - runtime library rc libgomp1:i386 4.6.3-1ubuntu5 GCC OpenMP (GOMP) support library rc libgpg-error0:i386 1.10-2ubuntu1 library for common error values and messages in GnuPG components rc libgphoto2-2:i386 2.4.13-1ubuntu1.2 gphoto2 digital camera library rc libgphoto2-port0:i386 2.4.13-1ubuntu1.2 gphoto2 digital camera port library rc libgssapi-krb5-2:i386 1.10+dfsg~beta1-2ubuntu0.3 MIT Kerberos runtime libraries - krb5 GSS-API Mechanism rc libgssapi3-heimdal:i386 1.6~git20120311.dfsg.1-2ubuntu0.1 Heimdal Kerberos - GSSAPI support library rc libgstreamer-plugins-base0.10-0:i386 0.10.36-1ubuntu0.1 GStreamer libraries from the "base" set rc libgstreamer0.10-0:i386 0.10.36-1ubuntu1 Core GStreamer libraries and elements rc libgtk2.0-0:i386 2.24.10-0ubuntu6 GTK+ graphical user interface library rc libgudev-1.0-0:i386 1:175-0ubuntu9.4 GObject-based wrapper library for libudev rc libhcrypto4-heimdal:i386 1.6~git20120311.dfsg.1-2ubuntu0.1 Heimdal Kerberos - crypto library rc libheimbase1-heimdal:i386 1.6~git20120311.dfsg.1-2ubuntu0.1 Heimdal Kerberos - Base library rc libheimntlm0-heimdal:i386 1.6~git20120311.dfsg.1-2ubuntu0.1 Heimdal Kerberos - NTLM support library rc libhx509-5-heimdal:i386 1.6~git20120311.dfsg.1-2ubuntu0.1 Heimdal Kerberos - X509 support library rc libibus-1.0-0:i386 1.4.1-3ubuntu1 Intelligent Input Bus - shared library rc libice6:i386 2:1.0.7-2build1 X11 Inter-Client Exchange library rc libidn11:i386 1.23-2 GNU Libidn library, implementation of IETF IDN specifications rc libiec61883-0:i386 1.2.0-0.1ubuntu1 an partial implementation of IEC 61883 rc libieee1284-3:i386 0.2.11-10build1 cross-platform library for parallel port access rc libjack-jackd2-0:i386 1.9.8~dfsg.1-1ubuntu2 JACK Audio Connection Kit (libraries) rc libjasper1:i386 1.900.1-13 JasPer JPEG-2000 runtime library rc libjpeg-turbo8:i386 1.1.90+svn733-0ubuntu4.2 IJG JPEG compliant runtime library. rc libjson0:i386 0.9-1ubuntu1 JSON manipulation library - shared library rc libk5crypto3:i386 1.10+dfsg~beta1-2ubuntu0.3 MIT Kerberos runtime libraries - Crypto Library rc libkeyutils1:i386 1.5.2-2 Linux Key Management Utilities (library) rc libkrb5-26-heimdal:i386 1.6~git20120311.dfsg.1-2ubuntu0.1 Heimdal Kerberos - libraries rc libkrb5-3:i386 1.10+dfsg~beta1-2ubuntu0.3 MIT Kerberos runtime libraries rc libkrb5support0:i386 1.10+dfsg~beta1-2ubuntu0.3 MIT Kerberos runtime libraries - Support library rc liblcms1:i386 1.19.dfsg-1ubuntu3 Little CMS color management library rc libldap-2.4-2:i386 2.4.28-1.1ubuntu4.4 OpenLDAP libraries rc libllvm3.0:i386 3.0-4ubuntu1 Low-Level Virtual Machine (LLVM), runtime library rc libllvm3.1:i386 3.1-2ubuntu1~12.04.1 Low-Level Virtual Machine (LLVM), runtime library rc libllvm3.2:i386 3.2-2ubuntu5~precise1 Low-Level Virtual Machine (LLVM), runtime library rc libltdl7:i386 2.4.2-1ubuntu1 A system independent dlopen wrapper for GNU libtool rc libmad0:i386 0.15.1b-7ubuntu1 MPEG audio decoder library rc libmikmod2:i386 3.1.12-2 Portable sound library rc libmng1:i386 1.0.10-3 Multiple-image Network Graphics library rc libmpg123-0:i386 1.12.1-3.2ubuntu1 MPEG layer 1/2/3 audio decoder -- runtime library rc libmysqlclient18:i386 5.5.32-0ubuntu0.12.04.1 MySQL database client library rc libnspr4:i386 4.9.5-0ubuntu0.12.04.1 NetScape Portable Runtime Library rc libnss3:i386 3.14.3-0ubuntu0.12.04.1 Network Security Service libraries rc libodbc1:i386 2.2.14p2-5ubuntu3 ODBC library for Unix rc libogg0:i386 1.2.2~dfsg-1ubuntu1 Ogg bitstream library rc libopenal1:i386 1:1.13-4ubuntu3 Software implementation of the OpenAL API (shared library) rc liborc-0.4-0:i386 1:0.4.16-1ubuntu2 Library of Optimized Inner Loops Runtime Compiler rc libosmesa6:i386 8.0.4-0ubuntu0.6 Mesa Off-screen rendering extension rc libp11-kit0:i386 0.12-2ubuntu1 Library for loading and coordinating access to PKCS#11 modules - runtime rc libpango1.0-0:i386 1.30.0-0ubuntu3.1 Layout and rendering of internationalized text rc libpixman-1-0:i386 0.24.4-1 pixel-manipulation library for X and cairo rc libproxy1:i386 0.4.7-0ubuntu4.1 automatic proxy configuration management library (shared) rc libpulse-mainloop-glib0:i386 1:1.1-0ubuntu15.4 PulseAudio client libraries (glib support) rc libpulse0:i386 1:1.1-0ubuntu15.4 PulseAudio client libraries rc libqt4-dbus:i386 4:4.8.1-0ubuntu4.4 Qt 4 D-Bus module rc libqt4-declarative:i386 4:4.8.1-0ubuntu4.4 Qt 4 Declarative module rc libqt4-designer:i386 4:4.8.1-0ubuntu4.4 Qt 4 designer module rc libqt4-network:i386 4:4.8.1-0ubuntu4.4 Qt 4 network module rc libqt4-opengl:i386 4:4.8.1-0ubuntu4.4 Qt 4 OpenGL module rc libqt4-qt3support:i386 4:4.8.1-0ubuntu4.4 Qt 3 compatibility library for Qt 4 rc libqt4-script:i386 4:4.8.1-0ubuntu4.4 Qt 4 script module rc libqt4-scripttools:i386 4:4.8.1-0ubuntu4.4 Qt 4 script tools module rc libqt4-sql:i386 4:4.8.1-0ubuntu4.4 Qt 4 SQL module rc libqt4-svg:i386 4:4.8.1-0ubuntu4.4 Qt 4 SVG module rc libqt4-test:i386 4:4.8.1-0ubuntu4.4 Qt 4 test module rc libqt4-xml:i386 4:4.8.1-0ubuntu4.4 Qt 4 XML module rc libqt4-xmlpatterns:i386 4:4.8.1-0ubuntu4.4 Qt 4 XML patterns module rc libqtcore4:i386 4:4.8.1-0ubuntu4.4 Qt 4 core module rc libqtgui4:i386 4:4.8.1-0ubuntu4.4 Qt 4 GUI module rc libqtwebkit4:i386 2.2.1-1ubuntu4 Web content engine library for Qt rc libraw1394-11:i386 2.0.7-1ubuntu1 library for direct access to IEEE 1394 bus (aka FireWire) rc libroken18-heimdal:i386 1.6~git20120311.dfsg.1-2ubuntu0.1 Heimdal Kerberos - roken support library rc librsvg2-2:i386 2.36.1-0ubuntu1 SAX-based renderer library for SVG files (runtime) rc librtmp0:i386 2.4~20110711.gitc28f1bab-1 toolkit for RTMP streams (shared library) rc libsamplerate0:i386 0.1.8-4 Audio sample rate conversion library rc libsane:i386 1.0.22-7ubuntu1 API library for scanners rc libsasl2-2:i386 2.1.25.dfsg1-3ubuntu0.1 Cyrus SASL - authentication abstraction library rc libsdl-image1.2:i386 1.2.10-3 image loading library for Simple DirectMedia Layer 1.2 rc libsdl-mixer1.2:i386 1.2.11-7 Mixer library for Simple DirectMedia Layer 1.2, libraries rc libsdl-net1.2:i386 1.2.7-5 Network library for Simple DirectMedia Layer 1.2, libraries rc libsdl-ttf2.0-0:i386 2.0.9-1.1ubuntu1 ttf library for Simple DirectMedia Layer with FreeType 2 support rc libsdl1.2debian:i386 1.2.14-6.4ubuntu3 Simple DirectMedia Layer rc libshout3:i386 2.2.2-7ubuntu1 MP3/Ogg Vorbis broadcast streaming library rc libsm6:i386 2:1.2.0-2build1 X11 Session Management library rc libsndfile1:i386 1.0.25-4 Library for reading/writing audio files rc libsoup-gnome2.4-1:i386 2.38.1-1 HTTP library implementation in C -- GNOME support library rc libsoup2.4-1:i386 2.38.1-1 HTTP library implementation in C -- Shared library rc libspeex1:i386 1.2~rc1-3ubuntu2 The Speex codec runtime library rc libspeexdsp1:i386 1.2~rc1-3ubuntu2 The Speex extended runtime library rc libsqlite3-0:i386 3.7.9-2ubuntu1.1 SQLite 3 shared library rc libssl0.9.8:i386 0.9.8o-7ubuntu3.1 SSL shared libraries rc libstdc++5:i386 1:3.3.6-25ubuntu1 The GNU Standard C++ Library v3 rc libstdc++6:i386 4.6.3-1ubuntu5 GNU Standard C++ Library v3 rc libtag1-vanilla:i386 1.7-1ubuntu5 audio meta-data library - vanilla flavour rc libtasn1-3:i386 2.10-1ubuntu1.1 Manage ASN.1 structures (runtime) rc libtdb1:i386 1.2.9-4 Trivial Database - shared library rc libthai0:i386 0.1.16-3 Thai language support library rc libtheora0:i386 1.1.1+dfsg.1-3ubuntu2 The Theora Video Compression Codec rc libtiff4:i386 3.9.5-2ubuntu1.5 Tag Image File Format (TIFF) library rc libtxc-dxtn-s2tc0:i386 0~git20110809-2.1 Texture compression library for Mesa rc libunistring0:i386 0.9.3-5 Unicode string library for C rc libusb-0.1-4:i386 2:0.1.12-20 userspace USB programming library rc libv4l-0:i386 0.8.6-1ubuntu2 Collection of video4linux support libraries rc libv4lconvert0:i386 0.8.6-1ubuntu2 Video4linux frame format conversion library rc libvisual-0.4-0:i386 0.4.0-4 Audio visualization framework rc libvorbis0a:i386 1.3.2-1ubuntu3 The Vorbis General Audio Compression Codec (Decoder library) rc libvorbisenc2:i386 1.3.2-1ubuntu3 The Vorbis General Audio Compression Codec (Encoder library) rc libvorbisfile3:i386 1.3.2-1ubuntu3 The Vorbis General Audio Compression Codec (High Level API) rc libwavpack1:i386 4.60.1-2 audio codec (lossy and lossless) - library rc libwind0-heimdal:i386 1.6~git20120311.dfsg.1-2ubuntu0.1 Heimdal Kerberos - stringprep implementation rc libwrap0:i386 7.6.q-21 Wietse Venema's TCP wrappers library rc libx11-6:i386 2:1.4.99.1-0ubuntu2.2 X11 client-side library rc libx11-xcb1:i386 2:1.4.99.1-0ubuntu2.2 Xlib/XCB interface library rc libxau6:i386 1:1.0.6-4 X11 authorisation library rc libxaw7:i386 2:1.0.9-3ubuntu1 X11 Athena Widget library rc libxcb-dri2-0:i386 1.8.1-1ubuntu0.2 X C Binding, dri2 extension rc libxcb-glx0:i386 1.8.1-1ubuntu0.2 X C Binding, glx extension rc libxcb-render0:i386 1.8.1-1ubuntu0.2 X C Binding, render extension rc libxcb-shm0:i386 1.8.1-1ubuntu0.2 X C Binding, shm extension rc libxcb1:i386 1.8.1-1ubuntu0.2 X C Binding rc libxcomposite1:i386 1:0.4.3-2build1 X11 Composite extension library rc libxcursor1:i386 1:1.1.12-1ubuntu0.1 X cursor management library rc libxdamage1:i386 1:1.1.3-2build1 X11 damaged region extension library rc libxdmcp6:i386 1:1.1.0-4 X11 Display Manager Control Protocol library rc libxext6:i386 2:1.3.0-3ubuntu0.1 X11 miscellaneous extension library rc libxfixes3:i386 1:5.0-4ubuntu4.1 X11 miscellaneous 'fixes' extension library rc libxft2:i386 2.2.0-3ubuntu2 FreeType-based font drawing library for X rc libxi6:i386 2:1.6.0-0ubuntu2.1 X11 Input extension library rc libxinerama1:i386 2:1.1.1-3ubuntu0.1 X11 Xinerama extension library rc libxml2:i386 2.7.8.dfsg-5.1ubuntu4.6 GNOME XML library rc libxmu6:i386 2:1.1.0-3 X11 miscellaneous utility library rc libxp6:i386 1:1.0.1-2ubuntu0.12.04.1 X Printing Extension (Xprint) client library rc libxpm4:i386 1:3.5.9-4 X11 pixmap library rc libxrandr2:i386 2:1.3.2-2ubuntu0.2 X11 RandR extension library rc libxrender1:i386 1:0.9.6-2ubuntu0.1 X Rendering Extension client library rc libxslt1.1:i386 1.1.26-8ubuntu1.3 XSLT 1.0 processing library - runtime library rc libxss1:i386 1:1.2.1-2 X11 Screen Saver extension library rc libxt6:i386 1:1.1.1-2ubuntu0.1 X11 toolkit intrinsics library rc libxtst6:i386 2:1.2.0-4ubuntu0.1 X11 Testing -- Record extension library rc libxv1:i386 2:1.0.6-2ubuntu0.1 X11 Video extension library rc libxxf86vm1:i386 1:1.1.1-2ubuntu0.1 X11 XFree86 video mode extension library rc odbcinst1debian2:i386 2.2.14p2-5ubuntu3 Support library for accessing odbc ini files rc skype-bin:i386 4.2.0.11-0ubuntu0.12.04.2 client for Skype VOIP and instant messaging service - binary files rc sni-qt:i386 0.2.5-0ubuntu3 indicator support for Qt rc wine-compholio:i386 1.7.4~ubuntu12.04.1 The Compholio Edition is a special build of the popular Wine software rc xaw3dg:i386 1.5+E-18.1ubuntu1 Xaw3d widget set

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  • Software Engineering Practices &ndash; Different Projects should have different maturity levels

    - by Dylan Smith
    I’ve had a lot of discussions at the office lately about the drastically different sets of software engineering practices used on our various projects, if what we are doing is appropriate, and what factors should you be considering when determining what practices are most appropriate in a given context. I wanted to write up my thoughts in a little more detail on this subject, so here we go: If you compare any two software projects (specifically comparing their codebases) you’ll often see very different levels of maturity in the software engineering practices employed. By software engineering practices, I’m specifically referring to the quality of the code and the amount of technical debt present in the project. Things such as Test Driven Development, Domain Driven Design, Behavior Driven Development, proper adherence to the SOLID principles, etc. are all practices that you would expect at the mature end of the spectrum. At the other end of the spectrum would be the quick-and-dirty solutions that are done using something like an Access Database, Excel Spreadsheet, or maybe some quick “drag-and-drop coding”. For this blog post I’m going to refer to this as the Software Engineering Maturity Spectrum (SEMS). I believe there is a time and a place for projects at every part of that SEMS. The risks and costs associated with under-engineering solutions have been written about a million times over so I won’t bother going into them again here, but there are also (unnecessary) costs with over-engineering a solution. Sometimes putting multiple layers, and IoC containers, and abstracting out the persistence, etc is complete overkill if a one-time use Access database could solve the problem perfectly well. A lot of software developers I talk to seem to automatically jump to the very right-hand side of this SEMS in everything they do. A common rationalization I hear is that it may seem like a small trivial application today, but these things always grow and stick around for many years, then you’re stuck maintaining a big ball of mud. I think this is a cop-out. Sure you can’t always anticipate how an application will be used or grow over its lifetime (can you ever??), but that doesn’t mean you can’t manage it and evolve the underlying software architecture as necessary (even if that means having to toss the code out and re-write it at some point…maybe even multiple times). My thoughts are that we should be making a conscious decision around the start of each project approximately where on the SEMS we want the project to exist. I believe this decision should be based on 3 factors: 1. Importance - How important to the business is this application? What is the impact if the application were to suddenly stop working? 2. Complexity - How complex is the application functionality? 3. Life-Expectancy - How long is this application expected to be in use? Is this a one-time use application, does it fill a short-term need, or is it more strategic and is expected to be in-use for many years to come? Of course this isn’t an exact science. You can’t say that Project X should be at the 73% mark on the SEMS and expect that to be helpful. My point is not that you need to precisely figure out what point on the SEMS the project should be at then translate that into some prescriptive set of practices and techniques you should be using. Rather my point is that we need to be aware that there is a spectrum, and that not everything is going to be (or should be) at the edges of that spectrum, indeed a large number of projects should probably fall somewhere within the middle; and different projects should adopt a different level of software engineering practices and maturity levels based on the needs of that project. To give an example of this way of thinking from my day job: Every couple of years my company plans and hosts a large event where ~400 of our customers all fly in to one location for a multi-day event with various activities. We have some staff whose job it is to organize the logistics of this event, which includes tracking which flights everybody is booked on, arranging for transportation to/from airports, arranging for hotel rooms, name tags, etc The last time we arranged this event all these various pieces of data were tracked in separate spreadsheets and reconciliation and cross-referencing of all the data was literally done by hand using printed copies of the spreadsheets and several people sitting around a table going down each list row by row. Obviously there is some room for improvement in how we are using software to manage the event’s logistics. The next time this event occurs we plan to provide the event planning staff with a more intelligent tool (either an Excel spreadsheet or probably an Access database) that can track all the information in one location and make sure that the various pieces of data are properly linked together (so for example if a person cancels you only need to delete them from one place, and not a dozen separate lists). This solution would fall at or near the very left end of the SEMS meaning that we will just quickly create something with very little attention paid to using mature software engineering practices. If we examine this project against the 3 criteria I listed above for determining it’s place within the SEMS we can see why: Importance – If this application were to stop working the business doesn’t grind to a halt, revenue doesn’t stop, and in fact our customers wouldn’t even notice since it isn’t a customer facing application. The impact would simply be more work for our event planning staff as they revert back to the previous way of doing things (assuming we don’t have any data loss). Complexity – The use cases for this project are pretty straightforward. It simply needs to manage several lists of data, and link them together appropriately. Precisely the task that access (and/or Excel) can do with minimal custom development required. Life-Expectancy – For this specific project we’re only planning to create something to be used for the one event (we only hold these events every 2 years). If it works well this may change (see below). Let’s assume we hack something out quickly and it works great when we plan the next event. We may decide that we want to make some tweaks to the tool and adopt it for planning all future events of this nature. In that case we should examine where the current application is on the SEMS, and make a conscious decision whether something needs to be done to move it further to the right based on the new objectives and goals for this application. This may mean scrapping the access database and re-writing it as an actual web or windows application. In this case, the life-expectancy changed, but let’s assume the importance and complexity didn’t change all that much. We can still probably get away with not adopting a lot of the so-called “best practices”. For example, we can probably still use some of the RAD tooling available and might have an Autonomous View style design that connects directly to the database and binds to typed datasets (we might even choose to simply leave it as an access database and continue using it; this is a decision that needs to be made on a case-by-case basis). At Anvil Digital we have aspirations to become a primarily product-based company. So let’s say we use this tool to plan a handful of events internally, and everybody loves it. Maybe a couple years down the road we decide we want to package the tool up and sell it as a product to some of our customers. In this case the project objectives/goals change quite drastically. Now the tool becomes a source of revenue, and the impact of it suddenly stopping working is significantly less acceptable. Also as we hold focus groups, and gather feedback from customers and potential customers there’s a pretty good chance the feature-set and complexity will have to grow considerably from when we were using it only internally for planning a small handful of events for one company. In this fictional scenario I would expect the target on the SEMS to jump to the far right. Depending on how we implemented the previous release we may be able to refactor and evolve the existing codebase to introduce a more layered architecture, a robust set of automated tests, introduce a proper ORM and IoC container, etc. More likely in this example the jump along the SEMS would be so large we’d probably end up scrapping the current code and re-writing. Although, if it was a slow phased roll-out to only a handful of customers, where we collected feedback, made some tweaks, and then rolled out to a couple more customers, we may be able to slowly refactor and evolve the code over time rather than tossing it out and starting from scratch. The key point I’m trying to get across is not that you should be throwing out your code and starting from scratch all the time. But rather that you should be aware of when and how the context and objectives around a project changes and periodically re-assess where the project currently falls on the SEMS and whether that needs to be adjusted based on changing needs. Note: There is also the idea of “spectrum decay”. Since our industry is rapidly evolving, what we currently accept as mature software engineering practices (the right end of the SEMS) probably won’t be the same 3 years from now. If you have a project that you were to assess at somewhere around the 80% mark on the SEMS today, but don’t touch the code for 3 years and come back and re-assess its position, it will almost certainly have changed since the right end of the SEMS will have moved farther out (maybe the project is now only around 60% due to decay). Developer Skills Another important aspect to this whole discussion is around the skill sets of your architects and lead developers. When talking about the progression of a developers skills from junior->intermediate->senior->… they generally start by only being able to write code that belongs on the left side of the SEMS and as they gain more knowledge and skill they become capable of working at a higher and higher level along the SEMS. We all realize that the learning never stops, but eventually you’ll get to the point where you can comfortably develop at the right-end of the SEMS (the exact practices and techniques that translates to is constantly changing, but that’s not the point here). A critical skill that I’d love to see more evidence of in our industry is the most senior guys not only being able to work at the right-end of the SEMS, but more importantly be able to consciously work at any point along the SEMS as project needs dictate. An even more valuable skill would be if you could make the conscious decision to move a projects code further right on the SEMS (based on changing needs) and do so in an incremental manner without having to start from scratch. An exercise that I’m planning to go through with all of our projects here at Anvil in the near future is to map out where I believe each project currently falls within this SEMS, where I believe the project *should* be on the SEMS based on the business needs, and for those that don’t match up (i.e. most of them) come up with a plan to improve the situation.

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  • CodePlex Daily Summary for Monday, March 29, 2010

    CodePlex Daily Summary for Monday, March 29, 2010New ProjectsBUtil: Backup toolcfDateTime: A library for conveniant dealing with date and time in code and UI.ComplexNetwork: Complex network is a network (graph) with non-trivial topological features—features that do not occur in simple networks such as lattices or random...Crash, Burn, Learn AI: Crash, Burn, Learn AI is a "social" AI that tries to learn a language. You provide it with words and it tries to speak.DashboardNET: Student project for Database Applications classDawf: Dual Audio Workflow: Dawf (Dual Audio Workflow) is a script for Sony Vegas Pro and PluralEyes. First, use PluralEyes to sync good audio from an external recorder (for ...EFDataPager: The EFDataPager is an Web User Control that provides Entity Framework data paging. This control enables your ListView, Datagrid or other data pres...GALOAP: GALOAP is a web framework for developing games with a purpose (or GWAP). A GWAP is a game played on a computer that serves some purpose for the peo...Modular CSharp Web Server: The Modular CSharp Web Server Is a small web server core that modules can be build to expand it.NHibernate Membership Provider: The NHMemberProvider is a complete .Net Membership Provider developed in C# and utilizing NHibernate for data persistence. NTP-VoIP Chat: NTP-VoIP chat is a sample VoIP based chat client (and server) developed for academic purposes at the Faculty of Electrical Engineering in Sarajevo....SharePoint Labs: SPLabs is a set of labs, either VB.NET or C#, focused on SharePoint technologies. Each lab is in itself a tutorial to learn a specific area of Shar...SharePoint Navigation Menu: Have a Web App with multiple site collections and need a common navigation menu? How about a SP Web Part that gives a consistent, easy to use, cen...Smebedor — greatest e-shop in the world: Smebedor - greatest e-shop in the worldStarksoft FTP and FTPS C# Client Library: Free, open source and easy to use .NET 2.0+ / Mono 2.x Component for connecting to FTP servers. Explicit and implicit SSL and TLS connections, dat...Sweet Office: The so Sweet Office built on the so sweet Silverlight.World Map WebPart: Display a world map and points several locations configured in the web part properties. The map is based on Google Maps and Live Maps.New ReleasesActivate Your Glutes: v1.0.2.0: An admin section has been added to the site and the log4net framework has been integrated. Minor tweak to registration to present a better date pic...ArkSwitch: ArkSwitch v1.1.4: Bugfix release, mainly for the new process mode.BatterySaver: Version 0.3: ChangeLog Add support for power change events in standby/hibernate (Issue) Add support for multiple configuration profiles (Issue) Added XSD for co...BUtil: BUtil 4.7: The initial releasecfDateTime: cfDateTime 0.1.1.3: This is the first public release of cfDateTime. Supported Features are: Base-implementation of the DateTimeSpan-type which is the logic-holder Im...Crash, Burn, Learn AI: Crash, Burn, Learn v0.1 Alpha: The first version of the AI. Got basic functionality but not everything works as it should so you're very welcome to test :)CycleMania Starter Kit EAP - ASP.NET 4 Problem - Design - Solution: Cyclemania 0.08.43: See Source Code tab for recent change history.Dawf: Dual Audio Workflow: Beta: Beta for DawfeCommerce by Onex Community Edition: Installer of eCommerce by Onex Community 1.0: Installer of eCommerce by Onex Community 1.0 Last changes: Added integration with Paypal Corrected of adding photos and attachments to products ...Encrypted Notes: Encrypted Notes 1.6.1: This is the latest version of Encrypted Notes (1.6.1), with bug fixes (mainly One-Time Pad). It has an installer - it will create a directory 'CPas...ExtAspNet: ExtAspNet v2.2.1: ExtAspNet v2.2.1 ExtAspNet is a set of professional Asp.net controls with native AJAX support and rich UI effect which aim at No JavaScript, No C...Load Test User Mock Toolkits: Open.LoadTest.User.Mock.Toolkits 1.0: 此版本为非正式版本,未对性能方面进行优化。而且框架正在重构调整中。miniTodo: mini Todo version 0.1: 超簡易TodoアプリMsmqJava: MsmqJava v1.2: MsmqJava v1.2 is an update of the Java/JNI wrapper for MSMQ. It is currently at v1.2.1.2. Last updated 28 March 2010. This version includes: ...N2 CMS: 2.0 beta2: Major Changes 2.0b-2.0b2 bugfixes prettified home interface analytics part icons for file types Major Changes 1.5-2.0b ASP.NET MVC 2 templat...New York Times Silverlight Kit: Version 1.0 for Windows Phone 7 Series: New York Times Silverlight Kit for Windows Phone 7 Series Release NotesDoes not include Articles or TimesTag APIsNHibernate Membership Provider: NHibernate Membership Provider 0.9b: This is the initial source code release of NHibernateProvider. I'm putting this up in beta for now, although it is currently being used in one of ...PowerShell ISE-Cream: PSISECream 0.1: So far, you must have downloaded the source code from this project and used the individual modules or scripts for different ISE addons. This projec...Prolog.NET: Prolog.NET 1.0 Beta 2: Installer includes: primary Prolog.NET assembly Prolog.NET Workbench Prolog.NET Scheduler sample application PrologTest console applicati...QuickStart Engine (3D Game Engine for XNA): QuickStart Engine v0.21: Main FeaturesClean engine architecture Makes it easy to make your own game using the engine. Messaging system allows you to communicate between s...S3Appender (Appender for Log4Net that Uses Amazon S3 For Storing Log Files): Stable Release 0.5: Download directly from source code http://s3appender.codeplex.com/SourceControl/changeset/view/43435SharePoint Labs: SPLab5001A-FRA-Level100: SPLab5001A-FRA-Level100 This SharePoint Lab will teach you how to increase your knowledge and use of CAML within Visual Studio. Lab Language : Fren...SharePoint Navigation Menu: spNavigationMenu 1.0: Inital release.Sweet Office: Simple drawing 0.0.1: A Visio-like simple drawing tool was built. Sweet Office is a Office-like tool set running on Silverlight.Switch Checker: v1.0.0.4 - Improved functionality: Added features: Add edit and delete options to right click switch list. Allow delete multiple switches from edit switches form. Allow copy MAC ...System.Common: System.Common Library: First release of System.Common.dlTeam 12 - Team FTW - Software Project: Quadrisauce Alpha Release: This is the first release of Quadrisauce!Visual Studio DSite: Math Wiz Quiz (Visual Basic 2008): A simple math quiz program, that test your knowledge of addition, subtraction and multiplication. This quiz is aimed for elementary kids, but you ...World Map WebPart: World Map Web Part v1.0: Display a world map and points several locations configured in the web part properties. The web part is using either Google Maps or Live Maps depen...WPF Dialogs: Version 0.2.0: 4 New Dialogs: NewFolderDialog / NewFolderDialog - Deutsch DeleteDialog / DeleteDialog - Deutsch] SaveDialog / SaveDialog- Deutsch RenamerDia...WPF Dialogs: Version 0.2.0 for .Net 3.5: The same new features like in the .Net 4 version Version 0.2.0ニコ生タイピング: Niconama Typing Ver. 10-03-28: ランキング 同順位の表示方法を変更 ランキング表示にスクロールバーを追加 切断ボタンを追加 スピードを5倍まで選択できるように変更 ニコ生の仕様変更に対応(運営コメント) デバッグ部分UI変更 NGワードを含む名前は登録できないように変更(含む場合、「名無し(NGコメ)...Most Popular ProjectsRawrWBFS ManagerASP.NET Ajax LibraryMicrosoft SQL Server Product Samples: DatabaseSilverlight ToolkitAJAX Control ToolkitLiveUpload to FacebookWindows Presentation Foundation (WPF)ASP.NETMicrosoft SQL Server Community & SamplesMost Active ProjectsRawrjQuery Library for SharePoint Web ServicesManaged Extensibility FrameworkLINQ to TwitterMicrosoft Biology FoundationBlogEngine.NETpatterns & practices: Composite WPF and SilverlightFarseer Physics EngineTable2ClassNB_Store - Free DotNetNuke Ecommerce Catalog Module

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  • C#/.NET Little Wonders: The Predicate, Comparison, and Converter Generic Delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last three weeks, we examined the Action family of delegates (and delegates in general), the Func family of delegates, and the EventHandler family of delegates and how they can be used to support generic, reusable algorithms and classes. This week I will be completing my series on the generic delegates in the .NET Framework with a discussion of three more, somewhat less used, generic delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>. These are older generic delegates that were introduced in .NET 2.0, mostly for use in the Array and List<T> classes.  Though older, it’s good to have an understanding of them and their intended purpose.  In addition, you can feel free to use them yourself, though obviously you can also use the equivalents from the Func family of delegates instead. Predicate<T> – delegate for determining matches The Predicate<T> delegate was a very early delegate developed in the .NET 2.0 Framework to determine if an item was a match for some condition in a List<T> or T[].  The methods that tend to use the Predicate<T> include: Find(), FindAll(), FindLast() Uses the Predicate<T> delegate to finds items, in a list/array of type T, that matches the given predicate. FindIndex(), FindLastIndex() Uses the Predicate<T> delegate to find the index of an item, of in a list/array of type T, that matches the given predicate. The signature of the Predicate<T> delegate (ignoring variance for the moment) is: 1: public delegate bool Predicate<T>(T obj); So, this is a delegate type that supports any method taking an item of type T and returning bool.  In addition, there is a semantic understanding that this predicate is supposed to be examining the item supplied to see if it matches a given criteria. 1: // finds first even number (2) 2: var firstEven = Array.Find(numbers, n => (n % 2) == 0); 3:  4: // finds all odd numbers (1, 3, 5, 7, 9) 5: var allEvens = Array.FindAll(numbers, n => (n % 2) == 1); 6:  7: // find index of first multiple of 5 (4) 8: var firstFiveMultiplePos = Array.FindIndex(numbers, n => (n % 5) == 0); This delegate has typically been succeeded in LINQ by the more general Func family, so that Predicate<T> and Func<T, bool> are logically identical.  Strictly speaking, though, they are different types, so a delegate reference of type Predicate<T> cannot be directly assigned to a delegate reference of type Func<T, bool>, though the same method can be assigned to both. 1: // SUCCESS: the same lambda can be assigned to either 2: Predicate<DateTime> isSameDayPred = dt => dt.Date == DateTime.Today; 3: Func<DateTime, bool> isSameDayFunc = dt => dt.Date == DateTime.Today; 4:  5: // ERROR: once they are assigned to a delegate type, they are strongly 6: // typed and cannot be directly assigned to other delegate types. 7: isSameDayPred = isSameDayFunc; When you assign a method to a delegate, all that is required is that the signature matches.  This is why the same method can be assigned to either delegate type since their signatures are the same.  However, once the method has been assigned to a delegate type, it is now a strongly-typed reference to that delegate type, and it cannot be assigned to a different delegate type (beyond the bounds of variance depending on Framework version, of course). Comparison<T> – delegate for determining order Just as the Predicate<T> generic delegate was birthed to give Array and List<T> the ability to perform type-safe matching, the Comparison<T> was birthed to give them the ability to perform type-safe ordering. The Comparison<T> is used in Array and List<T> for: Sort() A form of the Sort() method that takes a comparison delegate; this is an alternate way to custom sort a list/array from having to define custom IComparer<T> classes. The signature for the Comparison<T> delegate looks like (without variance): 1: public delegate int Comparison<T>(T lhs, T rhs); The goal of this delegate is to compare the left-hand-side to the right-hand-side and return a negative number if the lhs < rhs, zero if they are equal, and a positive number if the lhs > rhs.  Generally speaking, null is considered to be the smallest value of any reference type, so null should always be less than non-null, and two null values should be considered equal. In most sort/ordering methods, you must specify an IComparer<T> if you want to do custom sorting/ordering.  The Array and List<T> types, however, also allow for an alternative Comparison<T> delegate to be used instead, essentially, this lets you perform the custom sort without having to have the custom IComparer<T> class defined. It should be noted, however, that the LINQ OrderBy(), and ThenBy() family of methods do not support the Comparison<T> delegate (though one could easily add their own extension methods to create one, or create an IComparer() factory class that generates one from a Comparison<T>). So, given this delegate, we could use it to perform easy sorts on an Array or List<T> based on custom fields.  Say for example we have a data class called Employee with some basic employee information: 1: public sealed class Employee 2: { 3: public string Name { get; set; } 4: public int Id { get; set; } 5: public double Salary { get; set; } 6: } And say we had a List<Employee> that contained data, such as: 1: var employees = new List<Employee> 2: { 3: new Employee { Name = "John Smith", Id = 2, Salary = 37000.0 }, 4: new Employee { Name = "Jane Doe", Id = 1, Salary = 57000.0 }, 5: new Employee { Name = "John Doe", Id = 5, Salary = 60000.0 }, 6: new Employee { Name = "Jane Smith", Id = 3, Salary = 59000.0 } 7: }; Now, using the Comparison<T> delegate form of Sort() on the List<Employee>, we can sort our list many ways: 1: // sort based on employee ID 2: employees.Sort((lhs, rhs) => Comparer<int>.Default.Compare(lhs.Id, rhs.Id)); 3:  4: // sort based on employee name 5: employees.Sort((lhs, rhs) => string.Compare(lhs.Name, rhs.Name)); 6:  7: // sort based on salary, descending (note switched lhs/rhs order for descending) 8: employees.Sort((lhs, rhs) => Comparer<double>.Default.Compare(rhs.Salary, lhs.Salary)); So again, you could use this older delegate, which has a lot of logical meaning to it’s name, or use a generic delegate such as Func<T, T, int> to implement the same sort of behavior.  All this said, one of the reasons, in my opinion, that Comparison<T> isn’t used too often is that it tends to need complex lambdas, and the LINQ ability to order based on projections is much easier to use, though the Array and List<T> sorts tend to be more efficient if you want to perform in-place ordering. Converter<TInput, TOutput> – delegate to convert elements The Converter<TInput, TOutput> delegate is used by the Array and List<T> delegate to specify how to convert elements from an array/list of one type (TInput) to another type (TOutput).  It is used in an array/list for: ConvertAll() Converts all elements from a List<TInput> / TInput[] to a new List<TOutput> / TOutput[]. The delegate signature for Converter<TInput, TOutput> is very straightforward (ignoring variance): 1: public delegate TOutput Converter<TInput, TOutput>(TInput input); So, this delegate’s job is to taken an input item (of type TInput) and convert it to a return result (of type TOutput).  Again, this is logically equivalent to a newer Func delegate with a signature of Func<TInput, TOutput>.  In fact, the latter is how the LINQ conversion methods are defined. So, we could use the ConvertAll() syntax to convert a List<T> or T[] to different types, such as: 1: // get a list of just employee IDs 2: var empIds = employees.ConvertAll(emp => emp.Id); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.ConvertAll(emp => (int)emp.Salary); Note that the expressions above are logically equivalent to using LINQ’s Select() method, which gives you a lot more power: 1: // get a list of just employee IDs 2: var empIds = employees.Select(emp => emp.Id).ToList(); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.Select(emp => (int)emp.Salary).ToList(); The only difference with using LINQ is that many of the methods (including Select()) are deferred execution, which means that often times they will not perform the conversion for an item until it is requested.  This has both pros and cons in that you gain the benefit of not performing work until it is actually needed, but on the flip side if you want the results now, there is overhead in the behind-the-scenes work that support deferred execution (it’s supported by the yield return / yield break keywords in C# which define iterators that maintain current state information). In general, the new LINQ syntax is preferred, but the older Array and List<T> ConvertAll() methods are still around, as is the Converter<TInput, TOutput> delegate. Sidebar: Variance support update in .NET 4.0 Just like our descriptions of Func and Action, these three early generic delegates also support more variance in assignment as of .NET 4.0.  Their new signatures are: 1: // comparison is contravariant on type being compared 2: public delegate int Comparison<in T>(T lhs, T rhs); 3:  4: // converter is contravariant on input and covariant on output 5: public delegate TOutput Contravariant<in TInput, out TOutput>(TInput input); 6:  7: // predicate is contravariant on input 8: public delegate bool Predicate<in T>(T obj); Thus these delegates can now be assigned to delegates allowing for contravariance (going to a more derived type) or covariance (going to a less derived type) based on whether the parameters are input or output, respectively. Summary Today, we wrapped up our generic delegates discussion by looking at three lesser-used delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>.  All three of these tend to be replaced by their more generic Func equivalents in LINQ, but that doesn’t mean you shouldn’t understand what they do or can’t use them for your own code, as they do contain semantic meanings in their names that sometimes get lost in the more generic Func name.   Tweet Technorati Tags: C#,CSharp,.NET,Little Wonders,delegates,generics,Predicate,Converter,Comparison

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  • C#/.NET &ndash; Finding an Item&rsquo;s Index in IEnumerable&lt;T&gt;

    - by James Michael Hare
    Sorry for the long blogging hiatus.  First it was, of course, the holidays hustle and bustle, then my brother and his wife gave birth to their son, so I’ve been away from my blogging for two weeks. Background: Finding an item’s index in List<T> is easy… Many times in our day to day programming activities, we want to find the index of an item in a collection.  Now, if we have a List<T> and we’re looking for the item itself this is trivial: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // can find the exact item using IndexOf() 5: var pos = list.IndexOf(64); This will return the position of the item if it’s found, or –1 if not.  It’s easy to see how this works for primitive types where equality is well defined.  For complex types, however, it will attempt to compare them using EqualityComparer<T>.Default which, in a nutshell, relies on the object’s Equals() method. So what if we want to search for a condition instead of equality?  That’s also easy in a List<T> with the FindIndex() method: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // finds index of first even number or -1 if not found. 5: var pos = list.FindIndex(i => i % 2 == 0);   Problem: Finding an item’s index in IEnumerable<T> is not so easy... This is all well and good for lists, but what if we want to do the same thing for IEnumerable<T>?  A collection of IEnumerable<T> has no indexing, so there’s no direct method to find an item’s index.  LINQ, as powerful as it is, gives us many tools to get us this information, but not in one step.  As with almost any problem involving collections, there are several ways to accomplish the same goal.  And once again as with almost any problem involving collections, the choice of the solution somewhat depends on the situation. So let’s look at a few possible alternatives.  I’m going to express each of these as extension methods for simplicity and consistency. Solution: The TakeWhile() and Count() combo One of the things you can do is to perform a TakeWhile() on the list as long as your find condition is not true, and then do a Count() of the items it took.  The only downside to this method is that if the item is not in the list, the index will be the full Count() of items, and not –1.  So if you don’t know the size of the list beforehand, this can be confusing. 1: // a collection of extra extension methods off IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item in the collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // note if item not found, result is length and not -1! 8: return list.TakeWhile(i => !finder(i)).Count(); 9: } 10: } Personally, I don’t like switching the paradigm of not found away from –1, so this is one of my least favorites.  Solution: Select with index Many people don’t realize that there is an alternative form of the LINQ Select() method that will provide you an index of the item being selected: 1: list.Select( (item,index) => do something here with the item and/or index... ) This can come in handy, but must be treated with care.  This is because the index provided is only as pertains to the result of previous operations (if any).  For example: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // you'd hope this would give you the indexes of the even numbers 5: // which would be 2, 3, 8, but in reality it gives you 0, 1, 2 6: list.Where(item => item % 2 == 0).Select((item,index) => index); The reason the example gives you the collection { 0, 1, 2 } is because the where clause passes over any items that are odd, and therefore only the even items are given to the select and only they are given indexes. Conversely, we can’t select the index and then test the item in a Where() clause, because then the Where() clause would be operating on the index and not the item! So, what we have to do is to select the item and index and put them together in an anonymous type.  It looks ugly, but it works: 1: // extensions defined on IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // finds an item in a collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // if you don't name the anonymous properties they are the variable names 8: return list.Select((item, index) => new { item, index }) 9: .Where(p => finder(p.item)) 10: .Select(p => p.index + 1) 11: .FirstOrDefault() - 1; 12: } 13: }     So let’s look at this, because i know it’s convoluted: First Select() joins the items and their indexes into an anonymous type. Where() filters that list to only the ones matching the predicate. Second Select() picks the index of the matches and adds 1 – this is to distinguish between not found and first item. FirstOrDefault() returns the first item found from the previous clauses or default (zero) if not found. Subtract one so that not found (zero) will be –1, and first item (one) will be zero. The bad thing is, this is ugly as hell and creates anonymous objects for each item tested until it finds the match.  This concerns me a bit but we’ll defer judgment until compare the relative performances below. Solution: Convert ToList() and use FindIndex() This solution is easy enough.  We know any IEnumerable<T> can be converted to List<T> using the LINQ extension method ToList(), so we can easily convert the collection to a list and then just use the FindIndex() method baked into List<T>. 1: // a collection of extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // find the index of an item in the collection similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: return list.ToList().FindIndex(finder); 8: } 9: } This solution is simplicity itself!  It is very concise and elegant and you need not worry about anyone misinterpreting what it’s trying to do (as opposed to the more convoluted LINQ methods above). But the main thing I’m concerned about here is the performance hit to allocate the List<T> in the ToList() call, but once again we’ll explore that in a second. Solution: Roll your own FindIndex() for IEnumerable<T> Of course, you can always roll your own FindIndex() method for IEnumerable<T>.  It would be a very simple for loop which scans for the item and counts as it goes.  There’s many ways to do this, but one such way might look like: 1: // extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item matching a predicate in the enumeration, much like List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: int index = 0; 8: foreach (var item in list) 9: { 10: if (finder(item)) 11: { 12: return index; 13: } 14:  15: index++; 16: } 17:  18: return -1; 19: } 20: } Well, it’s not quite simplicity, and those less familiar with LINQ may prefer it since it doesn’t include all of the lambdas and behind the scenes iterators that come with deferred execution.  But does having this long, blown out method really gain us much in performance? Comparison of Proposed Solutions So we’ve now seen four solutions, let’s analyze their collective performance.  I took each of the four methods described above and run them over 100,000 iterations of lists of size 10, 100, 1000, and 10000 and here’s the performance results.  Then I looked for targets at the begining of the list (best case), middle of the list (the average case) and not in the list (worst case as must scan all of the list). Each of the times below is the average time in milliseconds for one execution as computer over the 100,000 iterations: Searches Matching First Item (Best Case)   10 100 1000 10000 TakeWhile 0.0003 0.0003 0.0003 0.0003 Select 0.0005 0.0005 0.0005 0.0005 ToList 0.0002 0.0003 0.0013 0.0121 Manual 0.0001 0.0001 0.0001 0.0001   Searches Matching Middle Item (Average Case)   10 100 1000 10000 TakeWhile 0.0004 0.0020 0.0191 0.1889 Select 0.0008 0.0042 0.0387 0.3802 ToList 0.0002 0.0007 0.0057 0.0562 Manual 0.0002 0.0013 0.0129 0.1255   Searches Where Not Found (Worst Case)   10 100 1000 10000 TakeWhile 0.0006 0.0039 0.0381 0.3770 Select 0.0012 0.0081 0.0758 0.7583 ToList 0.0002 0.0012 0.0100 0.0996 Manual 0.0003 0.0026 0.0253 0.2514   Notice something interesting here, you’d think the “roll your own” loop would be the most efficient, but it only wins when the item is first (or very close to it) regardless of list size.  In almost all other cases though and in particular the average case and worst case, the ToList()/FindIndex() combo wins for performance, even though it is creating some temporary memory to hold the List<T>.  If you examine the algorithm, the reason why is most likely because once it’s in a ToList() form, internally FindIndex() scans the internal array which is much more efficient to iterate over.  Thus, it takes a one time performance hit (not including any GC impact) to create the List<T> but after that the performance is much better. Summary If you’re concerned about too many throw-away objects, you can always roll your own FindIndex() method, but for sheer simplicity and overall performance, using the ToList()/FindIndex() combo performs best on nearly all list sizes in the average and worst cases.    Technorati Tags: C#,.NET,Litte Wonders,BlackRabbitCoder,Software,LINQ,List

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  • Visual Studio 2010 Productivity Tips and Tricks-Part 2: Key Shortcuts

    - by ToStringTheory
    Ask anyone that knows me, and they will confirm that I hate the mouse.  This isn’t because I deny affection to objects that don’t look like their mammalian-named self, but rather for a much more simple and not-insane reason: I have terrible eyesight.  Introduction Thanks to a degenerative eye disease known as Choroideremia, I have learned to rely more on the keyboard which I can feel digital/static positions of keys relative to my fingers, than the much more analog/random position of the mouse.  Now, I would like to share some of the keyboard shortcuts with you now, as I believe that they not only increase my productivity, but yours as well once you know them (if you don’t already of course)...  I share one of my biggest tips for productivity in the conclusion at the end. Visual Studio Key Shortcuts Global Editor Shortcuts These are shortcuts that are available from almost any application running in Windows, however are many times forgotten. Shortcut Action Visual Studio 2010 Functionality Ctrl + X Cut This shortcut works without a selection. If nothing is selected, the entire line that the caret is on is cut from the editor. Ctrl + C Copy This shortcut works without a selection. If nothing is selected, the entire line that the caret is on is copied from the editor. Ctrl + V Paste If you copied an entire line by the method above, the data is pasted in the line above the current caret line. Ctrl + Shift + V Next Clipboard Element Cut/Copy multiple things, and then hit this combo repeatedly to switch to the next clipboard item when pasting. Ctrl + Backspace Delete Previous Will delete the previous word from the editor directly before the caret. If anything is selected, will just delete that. Ctrl + Del Delete Next Word Will delete the next word/space from the editor directly after the caret. If anything is selected, will just delete that. Shift + Del Delete Focused Line Will delete the line from the editor that the caret is on. If something is selected, will just delete that. Ctrl + ? or Ctrl + ? Left/Right by Word This will move the caret left or right by word or special character boundary. Holding Shift will also select the word. Ctrl + F Quick Find Either the Quick Find panel, or the search bar if you have the Productivity Power Tools installed. Ctrl + Shift + F Find in Solution Opens up the 'Find in Files' window, allowing you to search your solution, as well as using regex for pattern matching. F2 Rename File... While not debugging, selecting a file in the solution explorer\navigator and pressing F2 allows you to rename the selected file. Global Application Shortcuts These are shortcuts that are available from almost any application running in Windows, however are many times forgotten... Again... Shortcut Action Visual Studio 2010 Functionality Ctrl + N New File dialog Opens up the 'New File' dialog to add a new file to the current directory in the Solution\Project. Ctrl + O Open File dialog Opens up the 'Open File' dialog to open a file in the editor, not necessarily in the solution. Ctrl + S Save File dialog Saves the currently focused editor tab back to your HDD/SSD. Ctrl + Shift + S Save All... Quickly save all open/edited documents back to your disk. Ctrl + Tab Switch Panel\Tab Tapping this combo switches between tabs quickly. Holding down Ctrl when hitting tab will bring up a chooser window. Building Shortcuts These are shortcuts that are focused on building and running a solution. These are not usable when the IDE is in Debug mode, as the shortcut changes by context. Shortcut Action Visual Studio 2010 Functionality Ctrl + Shift + B Build Solution Starts a build process on the solution according to the current build configuration manager settings. Ctrl + Break Cancel a Building Solution Will cancel a build operation currently in progress. Good for long running builds when you think of one last change. F5 Start Debugging Will build the solution if needed and launch debugging according to the current configuration manager settings. Ctrl + F5 Start Without Debugger Will build the solution if needed and launch the startup project without attaching a debugger. Debugging Shortcuts These are shortcuts that are used when debugging a solution. Shortcut Action Visual Studio 2010 Functionality F5 Continue Execution Continues execution of code until the next breakpoint. Ctrl + Alt + Break Pause Execution Pauses the program execution. Shift + F5 Stop Debugging Stops the current debugging session. NOTE: Web apps will still continue processing after stopping the debugger. Keep this in mind if working on code such as credit card processing. Ctrl + Shift + F5 Restart Debugging Stops the current debugging session and restarts the debugging session from the beginning. F9 Place Breakpoint Toggles/Places a breakpoint in the editor on the current line. Set a breakpoint in condensed code by highlighting the statement first. F10 Step Over Statement When debugging, executes all code in methods/properties on the current line until the next line. F11 Step Into Statement When debugging, steps into a method call so you can walk through the code executed there (if available). Ctrl + Alt + I Immediate Window Open the Immediate Window to execute commands when execution is paused. Navigation Shortcuts These are shortcuts that are used for navigating in the IDE or editor panel. Shortcut Action Visual Studio 2010 Functionality F4 Properties Panel Opens the properties panel for the selected item in the editor/designer/solution navigator (context driven). F12 Go to Definition Press F12 with the caret on a member to navigate to its declaration. With the Productivity tools, Ctrl + Click works too. Ctrl + K Ctrl + T View Call Hierarchy View the call hierarchy of the member the caret is on. Great for going through n-tier solutions and interface implementations! Ctrl + Alt + B Breakpoint Window View the breakpoint window to manage breakpoints and their advanced options. Allows easy toggling of breakpoints. Ctrl + Alt + L Solution Navigator Open the solution explorer panel. Ctrl + Alt + O Output Window View the output window to see build\general output from Visual Studio. Ctrl + Alt + Enter Live Web Preview Only available with the Web Essential plugin. Launches the auto-updating Preview panel. Testing Shortcuts These are shortcuts that are used for running tests in the IDE. Please note, Visual Studio 2010 is all about context. If your caret is within a test method when you use one of these combinations, the combination will apply to that test. If your caret is within a test class, it will apply to that class. If the caret is outside of a test class, it will apply to all tests. Shortcut Action Visual Studio 2010 Functionality Ctrl + R T Run Test(s) Run all tests in the current context without a debugger attached. Breakpoints will not be stopped on. Ctrl + R Ctrl + T Run Test(s) (Debug) Run all tests in the current context with a debugger attached. This allows you to use breakpoints. Substitute A for T from the preceding combos to run/debug ALL tests in the current context. Substitute Y for T from the preceding combos to run/debug ALL impacted/covering tests for a method in the current context. Advanced Editor Shortcuts These are shortcuts that are used for more advanced editing in the editor window. Shortcut Action Visual Studio 2010 Functionality Shift + Alt + ? Shift + Alt + ? Multiline caret up/down Use this combo to edit multiple lines at once. Not too many uses for it, but once in a blue moon one comes along. Ctrl + Alt + Enter Insert Line Above Inserts a blank line above the line the caret is currently on. No need to be at end or start of line, so no cutting off words/code. Ctrl + K Ctrl + C Comment Selection Comments the current selection out of compilation. Ctrl + K Ctrl + U Uncomment Selection Uncomments the current selection into compilation. Ctrl + K Ctrl + D Format Document Automatically formats the document into a structured layout. Lines up nodes or code into columns intelligently. Alt + ? Alt + ? Code line up/down *Use this combo to move a line of code up or down quickly. Great for small rearrangements of code. *Requires the Productivity Power pack from Microsoft. Conclusion This list is by no means meant to be exhaustive, but these are the shortcuts I use regularly every hour/minute of the day. There are still 100s more in Visual Studio that you can discover through the configuration window, or by tooltips. Something that I started doing months ago seems to have interest in my office.. In my last post, I talked about how I hated a cluttered UI. One of the ways that I aimed to resolve that was by systematically cleaning up the toolbars week by week. First day, I removed ALL icons that I already knew shortcuts to, or would never use them (Undo in a toolbar?!). Then, every week from that point on, I make it a point to remove an icon/two from the toolbar and make an effort to remember its key combination. I gain extra space in the toolbar area, AND become more productive at the same time! I hope that you found this article interesting or at least somewhat informative.. Maybe a shortcut or two you didn't know. I know some of them seem trivial, but I often see people going to the edit menu for Copy/Paste... Thought a refresher might be helpful!

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  • Set-Cookie Headers getting stripped in ASP.NET HttpHandlers

    - by Rick Strahl
    Yikes, I ran into a real bummer of an edge case yesterday in one of my older low level handler implementations (for West Wind Web Connection in this case). Basically this handler is a connector for a backend Web framework that creates self contained HTTP output. An ASP.NET Handler captures the full output, and then shoves the result down the ASP.NET Response object pipeline writing out the content into the Response.OutputStream and seperately sending the HttpHeaders in the Response.Headers collection. The headers turned out to be the problem and specifically Http Cookies, which for some reason ended up getting stripped out in some scenarios. My handler works like this: Basically the HTTP response from the backend app would return a full set of HTTP headers plus the content. The ASP.NET handler would read the headers one at a time and then dump them out via Response.AppendHeader(). But I found that in some situations Set-Cookie headers sent along were simply stripped inside of the Http Handler. After a bunch of back and forth with some folks from Microsoft (thanks Damien and Levi!) I managed to pin this down to a very narrow edge scenario. It's easiest to demonstrate the problem with a simple example HttpHandler implementation. The following simulates the very much simplified output generation process that fails in my handler. Specifically I have a couple of headers including a Set-Cookie header and some output that gets written into the Response object.using System.Web; namespace wwThreads { public class Handler : IHttpHandler { /* NOTE: * * Run as a web.config set handler (see entry below) * * Best way is to look at the HTTP Headers in Fiddler * or Chrome/FireBug/IE tools and look for the * WWHTREADSID cookie in the outgoing Response headers * ( If the cookie is not there you see the problem! ) */ public void ProcessRequest(HttpContext context) { HttpRequest request = context.Request; HttpResponse response = context.Response; // If ClearHeaders is used Set-Cookie header gets removed! // if commented header is sent... response.ClearHeaders(); response.ClearContent(); // Demonstrate that other headers make it response.AppendHeader("RequestId", "asdasdasd"); // This cookie gets removed when ClearHeaders above is called // When ClearHEaders is omitted above the cookie renders response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); // *** This always works, even when explicit // Set-Cookie above fails and ClearHeaders is called //response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); response.Write(@"Output was created.<hr/> Check output with Fiddler or HTTP Proxy to see whether cookie was sent."); } public bool IsReusable { get { return false; } } } } In order to see the problem behavior this code has to be inside of an HttpHandler, and specifically in a handler defined in web.config with: <add name=".ck_handler" path="handler.ck" verb="*" type="wwThreads.Handler" preCondition="integratedMode" /> Note: Oddly enough this problem manifests only when configured through web.config, not in an ASHX handler, nor if you paste that same code into an ASPX page or MVC controller. What's the problem exactly? The code above simulates the more complex code in my live handler that picks up the HTTP response from the backend application and then peels out the headers and sends them one at a time via Response.AppendHeader. One of the headers in my app can be one or more Set-Cookie. I found that the Set-Cookie headers were not making it into the Response headers output. Here's the Chrome Http Inspector trace: Notice, no Set-Cookie header in the Response headers! Now, running the very same request after removing the call to Response.ClearHeaders() command, the cookie header shows up just fine: As you might expect it took a while to track this down. At first I thought my backend was not sending the headers but after closer checks I found that indeed the headers were set in the backend HTTP response, and they were indeed getting set via Response.AppendHeader() in the handler code. Yet, no cookie in the output. In the simulated example the problem is this line:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); which in my live code is more dynamic ( ie. AppendHeader(token[0],token[1[]) )as it parses through the headers. Bizzaro Land: Response.ClearHeaders() causes Cookie to get stripped Now, here is where it really gets bizarre: The problem occurs only if: Response.ClearHeaders() was called before headers are added It only occurs in Http Handlers declared in web.config Clearly this is an edge of an edge case but of course - knowing my relationship with Mr. Murphy - I ended up running smack into this problem. So in the code above if you remove the call to ClearHeaders(), the cookie gets set!  Add it back in and the cookie is not there. If I run the above code in an ASHX handler it works. If I paste the same code (with a Response.End()) into an ASPX page, or MVC controller it all works. Only in the HttpHandler configured through Web.config does it fail! Cue the Twilight Zone Music. Workarounds As is often the case the fix for this once you know the problem is not too difficult. The difficulty lies in tracking inconsistencies like this down. Luckily there are a few simple workarounds for the Cookie issue. Don't use AppendHeader for Cookies The easiest and obvious solution to this problem is simply not use Response.AppendHeader() to set Cookies. Duh! Under normal circumstances in application level code there's rarely a reason to write out a cookie like this:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); but rather create the cookie using the Response.Cookies collection:response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); Unfortunately, in my case where I dynamically read headers from the original output and then dynamically  write header key value pairs back  programmatically into the Response.Headers collection, I actually don't look at each header specifically so in my case the cookie is just another header. My first thought was to simply trap for the Set-Cookie header and then parse out the cookie and create a Cookie object instead. But given that cookies can have a lot of different options this is not exactly trivial, plus I don't really want to fuck around with cookie values which can be notoriously brittle. Don't use Response.ClearHeaders() The real mystery in all this is why calling Response.ClearHeaders() prevents a cookie value later written with Response.AppendHeader() to fail. I fired up Reflector and took a quick look at System.Web and HttpResponse.ClearHeaders. There's all sorts of resetting going on but nothing that seems to indicate that headers should be removed later on in the request. The code in ClearHeaders() does access the HttpWorkerRequest, which is the low level interface directly into IIS, and so I suspect it's actually IIS that's stripping the headers and not ASP.NET, but it's hard to know. Somebody from Microsoft and the IIS team would have to comment on that. In my application it's probably safe to simply skip ClearHeaders() in my handler. The ClearHeaders/ClearContent was mainly for safety but after reviewing my code there really should never be a reason that headers would be set prior to this method firing. However, if for whatever reason headers do need to be cleared, it's easy enough to manually clear the headers out:private void RemoveHeaders(HttpResponse response) { List<string> headers = new List<string>(); foreach (string header in response.Headers) { headers.Add(header); } foreach (string header in headers) { response.Headers.Remove(header); } response.Cookies.Clear(); } Now I can replace the call the Response.ClearHeaders() and I don't get the funky side-effects from Response.ClearHeaders(). Summary I realize this is a total edge case as this occurs only in HttpHandlers that are manually configured. It looks like you'll never run into this in any of the higher level ASP.NET frameworks or even in ASHX handlers - only web.config defined handlers - which is really, really odd. After all those frameworks use the same underlying ASP.NET architecture. Hopefully somebody from Microsoft has an idea what crazy dependency was triggered here to make this fail. IAC, there are workarounds to this should you run into it, although I bet when you do run into it, it'll likely take a bit of time to find the problem or even this post in a search because it's not easily to correlate the problem to the solution. It's quite possible that more than cookies are affected by this behavior. Searching for a solution I read a few other accounts where headers like Referer were mysteriously disappearing, and it's possible that something similar is happening in those cases. Again, extreme edge case, but I'm writing this up here as documentation for myself and possibly some others that might have run into this. © Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET   IIS7   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • C#: Why Decorate When You Can Intercept

    - by James Michael Hare
    We've all heard of the old Decorator Design Pattern (here) or used it at one time or another either directly or indirectly.  A decorator is a class that wraps a given abstract class or interface and presents the same (or a superset) public interface but "decorated" with additional functionality.   As a really simplistic example, consider the System.IO.BufferedStream, it itself is a descendent of System.IO.Stream and wraps the given stream with buffering logic while still presenting System.IO.Stream's public interface:   1: Stream buffStream = new BufferedStream(rawStream); Now, let's take a look at a custom-code example.  Let's say that we have a class in our data access layer that retrieves a list of products from a database:  1: // a class that handles our CRUD operations for products 2: public class ProductDao 3: { 4: ... 5:  6: // a method that would retrieve all available products 7: public IEnumerable<Product> GetAvailableProducts() 8: { 9: var results = new List<Product>(); 10:  11: // must create the connection 12: using (var con = _factory.CreateConnection()) 13: { 14: con.ConnectionString = _productsConnectionString; 15: con.Open(); 16:  17: // create the command 18: using (var cmd = _factory.CreateCommand()) 19: { 20: cmd.Connection = con; 21: cmd.CommandText = _getAllProductsStoredProc; 22: cmd.CommandType = CommandType.StoredProcedure; 23:  24: // get a reader and pass back all results 25: using (var reader = cmd.ExecuteReader()) 26: { 27: while(reader.Read()) 28: { 29: results.Add(new Product 30: { 31: Name = reader["product_name"].ToString(), 32: ... 33: }); 34: } 35: } 36: } 37: }            38:  39: return results; 40: } 41: } Yes, you could use EF or any myriad other choices for this sort of thing, but the germaine point is that you have some operation that takes a non-trivial amount of time.  What if, during the production day I notice that my application is performing slowly and I want to see how much of that slowness is in the query versus my code.  Well, I could easily wrap the logic block in a System.Diagnostics.Stopwatch and log the results to log4net or other logging flavor of choice: 1:     // a class that handles our CRUD operations for products 2:     public class ProductDao 3:     { 4:         private static readonly ILog _log = LogManager.GetLogger(typeof(ProductDao)); 5:         ... 6:         7:         // a method that would retrieve all available products 8:         public IEnumerable<Product> GetAvailableProducts() 9:         { 10:             var results = new List<Product>(); 11:             var timer = Stopwatch.StartNew(); 12:             13:             // must create the connection 14:             using (var con = _factory.CreateConnection()) 15:             { 16:                 con.ConnectionString = _productsConnectionString; 17:                 18:                 // and all that other DB code... 19:                 ... 20:             } 21:             22:             timer.Stop(); 23:             24:             if (timer.ElapsedMilliseconds > 5000) 25:             { 26:                 _log.WarnFormat("Long query in GetAvailableProducts() took {0} ms", 27:                     timer.ElapsedMillseconds); 28:             } 29:             30:             return results; 31:         } 32:     } In my eye, this is very ugly.  It violates Single Responsibility Principle (SRP), which says that a class should only ever have one responsibility, where responsibility is often defined as a reason to change.  This class (and in particular this method) has two reasons to change: If the method of retrieving products changes. If the method of logging changes. Well, we could “simplify” this using the Decorator Design Pattern (here).  If we followed the pattern to the letter, we'd need to create a base decorator that implements the DAOs public interface and forwards to the wrapped instance.  So let's assume we break out the ProductDAO interface into IProductDAO using your refactoring tool of choice (Resharper is great for this). Now, ProductDao will implement IProductDao and get rid of all logging logic: 1:     public class ProductDao : IProductDao 2:     { 3:         // this reverts back to original version except for the interface added 4:     } 5:  And we create the base Decorator that also implements the interface and forwards all calls: 1:     public class ProductDaoDecorator : IProductDao 2:     { 3:         private readonly IProductDao _wrappedDao; 4:         5:         // constructor takes the dao to wrap 6:         public ProductDaoDecorator(IProductDao wrappedDao) 7:         { 8:             _wrappedDao = wrappedDao; 9:         } 10:         11:         ... 12:         13:         // and then all methods just forward their calls 14:         public IEnumerable<Product> GetAvailableProducts() 15:         { 16:             return _wrappedDao.GetAvailableProducts(); 17:         } 18:     } This defines our base decorator, then we can create decorators that add items of interest, and for any methods we don't decorate, we'll get the default behavior which just forwards the call to the wrapper in the base decorator: 1:     public class TimedThresholdProductDaoDecorator : ProductDaoDecorator 2:     { 3:         private static readonly ILog _log = LogManager.GetLogger(typeof(TimedThresholdProductDaoDecorator)); 4:         5:         public TimedThresholdProductDaoDecorator(IProductDao wrappedDao) : 6:             base(wrappedDao) 7:         { 8:         } 9:         10:         ... 11:         12:         public IEnumerable<Product> GetAvailableProducts() 13:         { 14:             var timer = Stopwatch.StartNew(); 15:             16:             var results = _wrapped.GetAvailableProducts(); 17:             18:             timer.Stop(); 19:             20:             if (timer.ElapsedMilliseconds > 5000) 21:             { 22:                 _log.WarnFormat("Long query in GetAvailableProducts() took {0} ms", 23:                     timer.ElapsedMillseconds); 24:             } 25:             26:             return results; 27:         } 28:     } Well, it's a bit better.  Now the logging is in its own class, and the database logic is in its own class.  But we've essentially multiplied the number of classes.  We now have 3 classes and one interface!  Now if you want to do that same logging decorating on all your DAOs, imagine the code bloat!  Sure, you can simplify and avoid creating the base decorator, or chuck it all and just inherit directly.  But regardless all of these have the problem of tying the logging logic into the code itself. Enter the Interceptors.  Things like this to me are a perfect example of when it's good to write an Interceptor using your class library of choice.  Sure, you could design your own perfectly generic decorator with delegates and all that, but personally I'm a big fan of Castle's Dynamic Proxy (here) which is actually used by many projects including Moq. What DynamicProxy allows you to do is intercept calls into any object by wrapping it with a proxy on the fly that intercepts the method and allows you to add functionality.  Essentially, the code would now look like this using DynamicProxy: 1: // Note: I like hiding DynamicProxy behind the scenes so users 2: // don't have to explicitly add reference to Castle's libraries. 3: public static class TimeThresholdInterceptor 4: { 5: // Our logging handle 6: private static readonly ILog _log = LogManager.GetLogger(typeof(TimeThresholdInterceptor)); 7:  8: // Handle to Castle's proxy generator 9: private static readonly ProxyGenerator _generator = new ProxyGenerator(); 10:  11: // generic form for those who prefer it 12: public static object Create<TInterface>(object target, TimeSpan threshold) 13: { 14: return Create(typeof(TInterface), target, threshold); 15: } 16:  17: // Form that uses type instead 18: public static object Create(Type interfaceType, object target, TimeSpan threshold) 19: { 20: return _generator.CreateInterfaceProxyWithTarget(interfaceType, target, 21: new TimedThreshold(threshold, level)); 22: } 23:  24: // The interceptor that is created to intercept the interface calls. 25: // Hidden as a private inner class so not exposing Castle libraries. 26: private class TimedThreshold : IInterceptor 27: { 28: // The threshold as a positive timespan that triggers a log message. 29: private readonly TimeSpan _threshold; 30:  31: // interceptor constructor 32: public TimedThreshold(TimeSpan threshold) 33: { 34: _threshold = threshold; 35: } 36:  37: // Intercept functor for each method invokation 38: public void Intercept(IInvocation invocation) 39: { 40: // time the method invocation 41: var timer = Stopwatch.StartNew(); 42:  43: // the Castle magic that tells the method to go ahead 44: invocation.Proceed(); 45:  46: timer.Stop(); 47:  48: // check if threshold is exceeded 49: if (timer.Elapsed > _threshold) 50: { 51: _log.WarnFormat("Long execution in {0} took {1} ms", 52: invocation.Method.Name, 53: timer.ElapsedMillseconds); 54: } 55: } 56: } 57: } Yes, it's a bit longer, but notice that: This class ONLY deals with logging long method calls, no DAO interface leftovers. This class can be used to time ANY class that has an interface or virtual methods. Personally, I like to wrap and hide the usage of DynamicProxy and IInterceptor so that anyone who uses this class doesn't need to know to add a Castle library reference.  As far as they are concerned, they're using my interceptor.  If I change to a new library if a better one comes along, they're insulated. Now, all we have to do to use this is to tell it to wrap our ProductDao and it does the rest: 1: // wraps a new ProductDao with a timing interceptor with a threshold of 5 seconds 2: IProductDao dao = TimeThresholdInterceptor.Create<IProductDao>(new ProductDao(), 5000); Automatic decoration of all methods!  You can even refine the proxy so that it only intercepts certain methods. This is ideal for so many things.  These are just some of the interceptors we've dreamed up and use: Log parameters and returns of methods to XML for auditing. Block invocations to methods and return default value (stubbing). Throw exception if certain methods are called (good for blocking access to deprecated methods). Log entrance and exit of a method and the duration. Log a message if a method takes more than a given time threshold to execute. Whether you use DynamicProxy or some other technology, I hope you see the benefits this adds.  Does it completely eliminate all need for the Decorator pattern?  No, there may still be cases where you want to decorate a particular class with functionality that doesn't apply to the world at large. But for all those cases where you are using Decorator to add functionality that's truly generic.  I strongly suggest you give this a try!

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  • Sharing the model in MVP Winforms App

    - by Keith G
    I'm working on building up an MVP application (C# Winforms). My initial version is at http://stackoverflow.com/questions/1422343/ ... Now I'm increasing the complexity. I've broken out the code to handle two separate text fields into two view/presenter pairs. It's a trivial example, but it's to work out the details of multiple presenters sharing the same model. My questions are about the model: I am basically using a property changed event raised by the model for notifying views that something has changed. Is that a good approach? What if it gets to the point where I have 100 or 1000 properties? Is it still practical at that point? Is instantiating the model in each presenter with   NoteModel _model = NoteModel.Instance   the correct approach? Note that I do want to make sure all of the presenters are sharing the same data. If there is a better approach, I'm open to suggestions .... My code looks like this: NoteModel.cs public class NoteModel : INotifyPropertyChanged { private static NoteModel _instance = null; public static NoteModel Instance { get { return _instance; } } static NoteModel() { _instance = new NoteModel(); } private NoteModel() { Initialize(); } public string Filename { get; set; } public bool IsDirty { get; set; } public readonly string DefaultName = "Untitled.txt"; string _sText; public string TheText { get { return _sText; } set { _sText = value; PropertyHasChanged("TheText"); } } string _sMoreText; public string MoreText { get { return _sMoreText; } set { _sMoreText = value; PropertyHasChanged("MoreText"); } } public void Initialize() { Filename = DefaultName; TheText = String.Empty; MoreText = String.Empty; IsDirty = false; } private void PropertyHasChanged(string sPropName) { IsDirty = true; if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(sPropName)); } } public event PropertyChangedEventHandler PropertyChanged; } TextEditorPresenter.cs public class TextEditorPresenter { ITextEditorView _view; NoteModel _model = NoteModel.Instance; public TextEditorPresenter(ITextEditorView view)//, NoteModel model) { //_model = model; _view = view; _model.PropertyChanged += new PropertyChangedEventHandler(model_PropertyChanged); } void model_PropertyChanged(object sender, PropertyChangedEventArgs e) { if (e.PropertyName == "TheText") _view.TheText = _model.TheText; } public void TextModified() { _model.TheText = _view.TheText; } public void ClearView() { _view.TheText = String.Empty; } } TextEditor2Presenter.cs is essentially the same except it operates on _model.MoreText instead of _model.TheText. ITextEditorView.cs public interface ITextEditorView { string TheText { get; set; } } ITextEditor2View.cs public interface ITextEditor2View { string MoreText { get; set; } }

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  • Python: Improving long cumulative sum

    - by Bo102010
    I have a program that operates on a large set of experimental data. The data is stored as a list of objects that are instances of a class with the following attributes: time_point - the time of the sample cluster - the name of the cluster of nodes from which the sample was taken code - the name of the node from which the sample was taken qty1 = the value of the sample for the first quantity qty2 = the value of the sample for the second quantity I need to derive some values from the data set, grouped in three ways - once for the sample as a whole, once for each cluster of nodes, and once for each node. The values I need to derive depend on the (time sorted) cumulative sums of qty1 and qty2: the maximum value of the element-wise sum of the cumulative sums of qty1 and qty2, the time point at which that maximum value occurred, and the values of qty1 and qty2 at that time point. I came up with the following solution: dataset.sort(key=operator.attrgetter('time_point')) # For the whole set sys_qty1 = 0 sys_qty2 = 0 sys_combo = 0 sys_max = 0 # For the cluster grouping cluster_qty1 = defaultdict(int) cluster_qty2 = defaultdict(int) cluster_combo = defaultdict(int) cluster_max = defaultdict(int) cluster_peak = defaultdict(int) # For the node grouping node_qty1 = defaultdict(int) node_qty2 = defaultdict(int) node_combo = defaultdict(int) node_max = defaultdict(int) node_peak = defaultdict(int) for t in dataset: # For the whole system ###################################################### sys_qty1 += t.qty1 sys_qty2 += t.qty2 sys_combo = sys_qty1 + sys_qty2 if sys_combo > sys_max: sys_max = sys_combo # The Peak class is to record the time point and the cumulative quantities system_peak = Peak(time_point=t.time_point, qty1=sys_qty1, qty2=sys_qty2) # For the cluster grouping ################################################## cluster_qty1[t.cluster] += t.qty1 cluster_qty2[t.cluster] += t.qty2 cluster_combo[t.cluster] = cluster_qty1[t.cluster] + cluster_qty2[t.cluster] if cluster_combo[t.cluster] > cluster_max[t.cluster]: cluster_max[t.cluster] = cluster_combo[t.cluster] cluster_peak[t.cluster] = Peak(time_point=t.time_point, qty1=cluster_qty1[t.cluster], qty2=cluster_qty2[t.cluster]) # For the node grouping ##################################################### node_qty1[t.node] += t.qty1 node_qty2[t.node] += t.qty2 node_combo[t.node] = node_qty1[t.node] + node_qty2[t.node] if node_combo[t.node] > node_max[t.node]: node_max[t.node] = node_combo[t.node] node_peak[t.node] = Peak(time_point=t.time_point, qty1=node_qty1[t.node], qty2=node_qty2[t.node]) This produces the correct output, but I'm wondering if it can be made more readable/Pythonic, and/or faster/more scalable. The above is attractive in that it only loops through the (large) dataset once, but unattractive in that I've essentially copied/pasted three copies of the same algorithm. To avoid the copy/paste issues of the above, I tried this also: def find_peaks(level, dataset): def grouping(object, attr_name): if attr_name == 'system': return attr_name else: return object.__dict__[attrname] cuml_qty1 = defaultdict(int) cuml_qty2 = defaultdict(int) cuml_combo = defaultdict(int) level_max = defaultdict(int) level_peak = defaultdict(int) for t in dataset: cuml_qty1[grouping(t, level)] += t.qty1 cuml_qty2[grouping(t, level)] += t.qty2 cuml_combo[grouping(t, level)] = (cuml_qty1[grouping(t, level)] + cuml_qty2[grouping(t, level)]) if cuml_combo[grouping(t, level)] > level_max[grouping(t, level)]: level_max[grouping(t, level)] = cuml_combo[grouping(t, level)] level_peak[grouping(t, level)] = Peak(time_point=t.time_point, qty1=node_qty1[grouping(t, level)], qty2=node_qty2[grouping(t, level)]) return level_peak system_peak = find_peaks('system', dataset) cluster_peak = find_peaks('cluster', dataset) node_peak = find_peaks('node', dataset) For the (non-grouped) system-level calculations, I also came up with this, which is pretty: dataset.sort(key=operator.attrgetter('time_point')) def cuml_sum(seq): rseq = [] t = 0 for i in seq: t += i rseq.append(t) return rseq time_get = operator.attrgetter('time_point') q1_get = operator.attrgetter('qty1') q2_get = operator.attrgetter('qty2') timeline = [time_get(t) for t in dataset] cuml_qty1 = cuml_sum([q1_get(t) for t in dataset]) cuml_qty2 = cuml_sum([q2_get(t) for t in dataset]) cuml_combo = [q1 + q2 for q1, q2 in zip(cuml_qty1, cuml_qty2)] combo_max = max(cuml_combo) time_max = timeline.index(combo_max) q1_at_max = cuml_qty1.index(time_max) q2_at_max = cuml_qty2.index(time_max) However, despite this version's cool use of list comprehensions and zip(), it loops through the dataset three times just for the system-level calculations, and I can't think of a good way to do the cluster-level and node-level calaculations without doing something slow like: timeline = defaultdict(int) cuml_qty1 = defaultdict(int) #...etc. for c in cluster_list: timeline[c] = [time_get(t) for t in dataset if t.cluster == c] cuml_qty1[c] = [q1_get(t) for t in dataset if t.cluster == c] #...etc. Does anyone here at Stack Overflow have suggestions for improvements? The first snippet above runs well for my initial dataset (on the order of a million records), but later datasets will have more records and clusters/nodes, so scalability is a concern. This is my first non-trivial use of Python, and I want to make sure I'm taking proper advantage of the language (this is replacing a very convoluted set of SQL queries, and earlier versions of the Python version were essentially very ineffecient straight transalations of what that did). I don't normally do much programming, so I may be missing something elementary. Many thanks!

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  • Adding objects to the environment at timed intervals

    - by david
    I am using an ArrayList to handle objects and at each interval of 120 frames, I am adding a new object of the same type at a random location along the z-axis of 60. The problem is, it doesn't add just 1. It depends on how many are in the list. If I kill the Fox before the time interval when one is supposed to spawn comes, then no Fox will be spawned. If I don't kill any foxes, it grows exponentially. I only want one Fox to be added every 120 frames. This problem never happened before when I created new ones and added them to the environment. Any insights? Here is my code: /**** FOX CLASS ****/ import env3d.EnvObject; import java.util.ArrayList; public class Fox extends Creature { private int frame = 0; public Fox(double x, double y, double z) { super(x, y, z); // Must use the mutator as the fields have private access // in the parent class setTexture("models/fox/fox.png"); setModel("models/fox/fox.obj"); setScale(1.4); } public void move(ArrayList<Creature> creatures, ArrayList<Creature> dead_creatures, ArrayList<Creature> new_creatures) { frame++; setX(getX()-0.2); setRotateY(270); if (frame > 120) { Fox f = new Fox(60, 1, (int)(Math.random()*28)+1); new_creatures.add(f); frame = 0; } for (Creature c : creatures) { if (this.distance(c) < this.getScale()+c.getScale() && c instanceof Tux) { dead_creatures.add(c); } } for (Creature c : creatures) { if (c.getX() < 1 && c instanceof Fox) { dead_creatures.add(c); } } } } import env3d.Env; import java.util.ArrayList; import org.lwjgl.input.Keyboard; /** * A predator and prey simulation. Fox is the predator and Tux is the prey. */ public class Game { private Env env; private boolean finished; private ArrayList<Creature> creatures; private KingTux king; private Snowball ball; private int tuxcounter; private int kills; /** * Constructor for the Game class. It sets up the foxes and tuxes. */ public Game() { // we use a separate ArrayList to keep track of each animal. // our room is 50 x 50. creatures = new ArrayList<Creature>(); for (int i = 0; i < 10; i++) { creatures.add(new Tux((int)(Math.random()*10)+1, 1, (int)(Math.random()*28)+1)); } for (int i = 0; i < 1; i++) { creatures.add(new Fox(60, 1, (int)(Math.random()*28)+1)); } king = new KingTux(25, 1, 35); ball = new Snowball(-400, -400, -400); } /** * Play the game */ public void play() { finished = false; // Create the new environment. Must be done in the same // method as the game loop env = new Env(); // Make the room 50 x 50. env.setRoom(new Room()); // Add all the animals into to the environment for display for (Creature c : creatures) { env.addObject(c); } for (Creature c : creatures) { if (c instanceof Tux) { tuxcounter++; } } env.addObject(king); env.addObject(ball); // Sets up the camera env.setCameraXYZ(30, 50, 55); env.setCameraPitch(-63); // Turn off the default controls env.setDefaultControl(false); // A list to keep track of dead tuxes. ArrayList<Creature> dead_creatures = new ArrayList<Creature>(); ArrayList<Creature> new_creatures = new ArrayList<Creature>(); // The main game loop while (!finished) { if (env.getKey() == 1 || tuxcounter == 0) { finished = true; } env.setDisplayStr("Tuxes: " + tuxcounter, 15, 0); env.setDisplayStr("Kills: " + kills, 140, 0); processInput(); ball.move(); king.check(); // Move each fox and tux. for (Creature c : creatures) { c.move(creatures, dead_creatures, new_creatures); } for (Creature c : creatures) { if (c.distance(ball) < c.getScale()+ball.getScale() && c instanceof Fox) { dead_creatures.add(c); ball.setX(-400); ball.setY(-400); ball.setZ(-400); kills++; } } // Clean up of the dead tuxes. for (Creature c : dead_creatures) { if (c instanceof Tux) { tuxcounter--; } env.removeObject(c); creatures.remove(c); } for (Creature c : new_creatures) { creatures.add(c); env.addObject(c); } // we clear the ArrayList for the next loop. We could create a new one // every loop but that would be very inefficient. dead_creatures.clear(); new_creatures.clear(); // Update display env.advanceOneFrame(); } // Just a little clean up env.exit(); } private void processInput() { int keyDown = env.getKeyDown(); int key = env.getKey(); if (keyDown == 203) { king.setX(king.getX()-1); } else if (keyDown == 205) { king.setX(king.getX()+1); } if (ball.getX() <= -400 && key == Keyboard.KEY_S) { ball.setX(king.getX()); ball.setY(king.getY()); ball.setZ(king.getZ()); } } /** * Main method to launch the program. */ public static void main(String args[]) { (new Game()).play(); } } /**** CREATURE CLASS ****/ /* (Parent class to Tux, Fox, and KingTux) */ import env3d.EnvObject; import java.util.ArrayList; abstract public class Creature extends EnvObject { private int frame; private double rand; /** * Constructor for objects of class Creature */ public Creature(double x, double y, double z) { setX(x); setY(y); setZ(z); setScale(1); rand = Math.random(); } private void randomGenerator() { rand = Math.random(); } public void move(ArrayList<Creature> creatures, ArrayList<Creature> dead_creatures, ArrayList<Creature> new_creatures) { frame++; if (frame > 12) { randomGenerator(); frame = 0; } // if (rand < 0.25) { // setX(getX()+0.3); // setRotateY(90); // } else if (rand < 0.5) { // setX(getX()-0.3); // setRotateY(270); // } else if (rand < 0.75) { // setZ(getZ()+0.3); // setRotateY(0); // } else if (rand < 1) { // setZ(getZ()-0.3); // setRotateY(180); // } if (rand < 0.5) { setRotateY(getRotateY()-7); } else if (rand < 1) { setRotateY(getRotateY()+7); } setX(getX()+Math.sin(Math.toRadians(getRotateY()))*0.5); setZ(getZ()+Math.cos(Math.toRadians(getRotateY()))*0.5); if (getX() < getScale()) setX(getScale()); if (getX() > 50-getScale()) setX(50 - getScale()); if (getZ() < getScale()) setZ(getScale()); if (getZ() > 50-getScale()) setZ(50 - getScale()); // The move method now handles collision detection if (this instanceof Fox) { for (Creature c : creatures) { if (c.distance(this) < c.getScale()+this.getScale() && c instanceof Tux) { dead_creatures.add(c); } } } } } The rest of the classes are a bit trivial to this specific problem.

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  • CodePlex Daily Summary for Tuesday, June 18, 2013

    CodePlex Daily Summary for Tuesday, June 18, 2013Popular ReleasesCODE Framework: 4.0.30618.0: See change notes in the documentation section for details on what's new. Note: If you download the class reference help file with, you have to right-click the file, pick "Properties", and then unblock the file, as many browsers flag the file as blocked during download (for security reasons) and thus hides all content.Toolbox for Dynamics CRM 2011: XrmToolBox (v1.2013.6.18): XrmToolbox improvement Use new connection controls (use of Microsoft.Xrm.Client.dll) New display capabilities for tools (size, image and colors) Added prerequisites check Added Most Used Tools feature Tools improvementNew toolSolution Transfer Tool (v1.0.0.0) developed by DamSim Updated toolView Layout Replicator (v1.2013.6.17) Double click on source view to display its layoutXml All tools list Access Checker (v1.2013.6.17) Attribute Bulk Updater (v1.2013.6.18) FetchXml Tester (v1.2013.6.1...Media Companion: Media Companion MC3.570b: New* Movie - using XBMC TMDB - now renames movies if option selected. * Movie - using Xbmc Tmdb - Actor images saved from TMDb if option selected. Fixed* Movie - Checks for poster.jpg against missing poster filter * Movie - Fixed continual scraping of vob movie file (not DVD structure) * Both - Correctly display audio channels * Both - Correctly populate audio info in nfo's if multiple audio tracks. * Both - added icons and checked for DTS ES and Dolby TrueHD audio tracks. * Both - Stream d...LINQ Extensions Library: 1.0.4.2: New to release 1.0.4.2 Custom sorting extensions that perform up to 50% better than LINQ OrderBy, ThenBy extensions... Extensions allow for fine tuning of the sort by controlling the algorithm each sort uses.ExtJS based ASP.NET Controls: FineUI v3.3.0: ??FineUI ?? ExtJS ??? ASP.NET ???。 FineUI??? ?? No JavaScript,No CSS,No UpdatePanel,No ViewState,No WebServices ???????。 ?????? IE 7.0、Firefox 3.6、Chrome 3.0、Opera 10.5、Safari 3.0+ ???? Apache License v2.0 ?:ExtJS ?? GPL v3 ?????(http://www.sencha.com/license)。 ???? ??:http://fineui.com/bbs/ ??:http://fineui.com/demo/ ??:http://fineui.com/doc/ ??:http://fineui.codeplex.com/ FineUI???? ExtJS ?????????,???? ExtJS ?。 ????? FineUI ? ExtJS ?:http://fineui.com/bbs/forum.php?mod=viewthrea...BarbaTunnel: BarbaTunnel 8.0: Check Version History for more information about this release.ExpressProfiler: ExpressProfiler v1.5: [+] added Start time, End time event columns [+] added SP:StmtStarting, SP:StmtCompleted events [*] fixed bug with Audit:Logout eventpatterns & practices: Data Access Guidance: Data Access Guidance Drop4 2013.06.17: Drop 4Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.94: add dstLine and dstCol attributes to the -Analyze output in XML mode. un-combine leftover comma-separates expression statements after optimizations are complete so downstream tools don't stack-overflow on really deep comma trees. add support for using a single source map generator instance with multiple runs of MinifyJavaScript, assuming that the results are concatenated to the same output file.Kooboo CMS: Kooboo CMS 4.1.1: The stable release of Kooboo CMS 4.1.0 with fixed the following issues: https://github.com/Kooboo/CMS/issues/1 https://github.com/Kooboo/CMS/issues/11 https://github.com/Kooboo/CMS/issues/13 https://github.com/Kooboo/CMS/issues/15 https://github.com/Kooboo/CMS/issues/19 https://github.com/Kooboo/CMS/issues/20 https://github.com/Kooboo/CMS/issues/24 https://github.com/Kooboo/CMS/issues/43 https://github.com/Kooboo/CMS/issues/45 https://github.com/Kooboo/CMS/issues/46 https://github....VidCoder: 1.5.0 Beta: The betas have started up again! If you were previously on the beta track you will need to install this to get back on it. That's because you can now run both the Beta and Stable version of VidCoder side-by-side! Note that the OpenCL and Intel QuickSync changes being tested by HandBrake are not in the betas yet. They will appear when HandBrake integrates them into the main branch. Updated HandBrake core to SVN 5590. This adds a new FDK AAC encoder. The FAAC encoder has been removed and now...Employee Info Starter Kit: v6.0 - ASP.NET MVC Edition: Release Home - Getting Started - Hands on Coding Walkthrough – Technology Stack - Design & Architecture EISK v6.0 – ASP.NET MVC edition bundles most of the greatest and successful platforms, frameworks and technologies together, to enable web developers to learn and build manageable and high performance web applications with rich user experience effectively and quickly. User End SpecificationsCreating a new employee record Read existing employee records Update an existing employee reco...OLAP PivotTable Extensions: Release 0.8.1: Use the 32-bit download for... Excel 2007 Excel 2010 32-bit (even Excel 2010 32-bit on a 64-bit operating system) Excel 2013 32-bit (even Excel 2013 32-bit on a 64-bit operating system) Use the 64-bit download for... Excel 2010 64-bit Excel 2013 64-bit Just download and run the EXE. There is no need to uninstall the previous release. If you have problems getting the add-in to work, see the Troubleshooting Installation wiki page. The new features in this release are: View #VALUE! Err...DirectXTex texture processing library: June 2013: June 15, 2013 Custom filtering implementation for Resize & GenerateMipMaps(3D) - Point, Box, Linear, Cubic, and Triangle TEX_FILTER_TRIANGLE finite low-pass triangle filter TEX_FILTER_WRAP, TEX_FILTER_MIRROR texture semantics for custom filtering TEX_FILTER_BOX alias for TEX_FILTER_FANT WIC Ordered and error diffusion dithering for non-WIC conversion sRGB gamma correct custom filtering and conversion DDS_FLAGS_EXPAND_LUMINANCE - Reader conversion option for L8, L16, and A8L8 legacy ...WPF Application Framework (WAF): WPF Application Framework (WAF) 3.0.0.440: Version: 3.0.0.440 (Release Candidate): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Please build the whole solution before you start one of the sample applications. Requirements .NET Framework 4.5 (The package contains a solution file for Visual Studio 2012) Changelog Legend: [B] Breaking change; [O] Marked member as obsolete Samples: Use ValueConverters via StaticResource instead of x:Static. Other Downloads Downloads OverviewBlackJumboDog: Ver5.9.1: 2013.06.13 Ver5.9.1 (1) Web??????SSI?#include???、CGI?????????????????????? (2) ???????????????????????????Lakana - WPF Framework: Lakana V2.1 RTM: - Dynamic text localization - A new application wide message busFree language translator and file converter: Free Language Translator 3.3: some bug fixes and a new link to video tutorials on Youtube.Pokemon Battle Online: ETV: ETV???2012?12??????,????,???????$/PBO/branches/PrivateBeta??。 ???????bug???????。 ???? Server??????,?????。 ?????????,?????????????,?????????。 ????????,????,?????????,???????????(??)??。 ???? ????????????。 ???????。 ???PP????,????????????????????PP????,??3。 ?????????????,??????????。 ???????? ??? ?? ???? ??? ???? ?? ?????????? ?? ??? ??? ??? ???????? ???? ???? ???????????????、???????????,??“???????”??。 ???bug ???Modern UI for WPF: Modern UI 1.0.4: The ModernUI assembly including a demo app demonstrating the various features of Modern UI for WPF. Related downloads NuGet ModernUI for WPF is also available as NuGet package in the NuGet gallery, id: ModernUI.WPF Download Modern UI for WPF Templates A Visual Studio 2012 extension containing a collection of project and item templates for Modern UI for WPF. The extension includes the ModernUI.WPF NuGet package. DownloadNew ProjectsAux Browser: This browser is secured by system level sandbox technology, and it helps you get where you want to go in the shortest possible time. Best solution to convert Outlook OST to PST files: Convert OST to PST without fearing for data loss. An immaculate converter by Recover Data gives user a privilege to perform OST file recovery with no data loss.Bitbucket.NET: A high-performance .NET library for developing applications that use the Bitbucket service.caosu: aaaChartApp: Chart App for SharePoint 2013Custom Membership Provider SQL + LDAP with one login page: Custom membership provider to allow users to login to there portal from one login page whether its custom SQLDB or the current Active Directory.DroidBrowse: Web browser for Android 1.6 or later.haseebtestProject: This project is created to add random files and for testing purposesHiveSense: Hive monitoring system.JQuery File Upload Plugin with Backload server side component (Demo/Examples): Backload is a professional, full featured ASP.NET MVC 4 file upload controller and handler (server side). JSLocator: Locate javascript functions in the sourceMoonCMS: This is a trivial thing. It doesn't make any sense!MyLabs: MyLabs is Private Labpcvvpes: pcvvpesPrism Model Factory Extensions: Micro framework for model cloning, equality check and mergingSharePoint 2007 Solution and Packaging Guidance: WSPSolution is a standard for building SP 2007 solutions in Visual Studio, namespace planning, deployment planning, WSP creation, and build automation.Windows Phone Wi-Fi Launcher: Wi-Fi settings page launcher for Windows Phone 8.0

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  • Code Reuse is (Damn) Hard

    - by James Michael Hare
    Being a development team lead, the task of interviewing new candidates was part of my job.  Like any typical interview, we started with some easy questions to get them warmed up and help calm their nerves before hitting the hard stuff. One of those easier questions was almost always: “Name some benefits of object-oriented development.”  Nearly every time, the candidate would chime in with a plethora of canned answers which typically included: “it helps ease code reuse.”  Of course, this is a gross oversimplification.  Tools only ease reuse, its developers that ultimately can cause code to be reusable or not, regardless of the language or methodology. But it did get me thinking…  we always used to say that as part of our mantra as to why Object-Oriented Programming was so great.  With polymorphism, inheritance, encapsulation, etc. we in essence set up the concepts to help facilitate reuse as much as possible.  And yes, as a developer now of many years, I unquestionably held that belief for ages before it really struck me how my views on reuse have jaded over the years.  In fact, in many ways Agile rightly eschews reuse as taking a backseat to developing what's needed for the here and now.  It used to be I was in complete opposition to that view, but more and more I've come to see the logic in it.  Too many times I've seen developers (myself included) get lost in design paralysis trying to come up with the perfect abstraction that would stand all time.  Nearly without fail, all of these pieces of code become obsolete in a matter of months or years. It’s not that I don’t like reuse – it’s just that reuse is hard.  In fact, reuse is DAMN hard.  Many times it is just a distraction that eats up architect and developer time, and worse yet can be counter-productive and force wrong decisions.  Now don’t get me wrong, I love the idea of reusable code when it makes sense.  These are in the few cases where you are designing something that is inherently reusable.  The problem is, most business-class code is inherently unfit for reuse! Furthermore, the code that is reusable will often fail to be reused if you don’t have the proper framework in place for effective reuse that includes standardized versioning, building, releasing, and documenting the components.  That should always be standard across the board when promoting reusable code.  All of this is hard, and it should only be done when you have code that is truly reusable or you will be exerting a large amount of development effort for very little bang for your buck. But my goal here is not to get into how to reuse (that is a topic unto itself) but what should be reused.  First, let’s look at an extension method.  There’s many times where I want to kick off a thread to handle a task, then when I want to reign that thread in of course I want to do a Join on it.  But what if I only want to wait a limited amount of time and then Abort?  Well, I could of course write that logic out by hand each time, but it seemed like a great extension method: 1: public static class ThreadExtensions 2: { 3: public static bool JoinOrAbort(this Thread thread, TimeSpan timeToWait) 4: { 5: bool isJoined = false; 6:  7: if (thread != null) 8: { 9: isJoined = thread.Join(timeToWait); 10:  11: if (!isJoined) 12: { 13: thread.Abort(); 14: } 15: } 16: return isJoined; 17: } 18: } 19:  When I look at this code, I can immediately see things that jump out at me as reasons why this code is very reusable.  Some of them are standard OO principles, and some are kind-of home grown litmus tests: Single Responsibility Principle (SRP) – The only reason this extension method need change is if the Thread class itself changes (one responsibility). Stable Dependencies Principle (SDP) – This method only depends on classes that are more stable than it is (System.Threading.Thread), and in itself is very stable, hence other classes may safely depend on it. It is also not dependent on any business domain, and thus isn't subject to changes as the business itself changes. Open-Closed Principle (OCP) – This class is inherently closed to change. Small and Stable Problem Domain – This method only cares about System.Threading.Thread. All-or-None Usage – A user of a reusable class should want the functionality of that class, not parts of that functionality.  That’s not to say they most use every method, but they shouldn’t be using a method just to get half of its result. Cost of Reuse vs. Cost to Recreate – since this class is highly stable and minimally complex, we can offer it up for reuse very cheaply by promoting it as “ready-to-go” and already unit tested (important!) and available through a standard release cycle (very important!). Okay, all seems good there, now lets look at an entity and DAO.  I don’t know about you all, but there have been times I’ve been in organizations that get the grand idea that all DAOs and entities should be standardized and shared.  While this may work for small or static organizations, it’s near ludicrous for anything large or volatile. 1: namespace Shared.Entities 2: { 3: public class Account 4: { 5: public int Id { get; set; } 6:  7: public string Name { get; set; } 8:  9: public Address HomeAddress { get; set; } 10:  11: public int Age { get; set;} 12:  13: public DateTime LastUsed { get; set; } 14:  15: // etc, etc, etc... 16: } 17: } 18:  19: ... 20:  21: namespace Shared.DataAccess 22: { 23: public class AccountDao 24: { 25: public Account FindAccount(int id) 26: { 27: // dao logic to query and return account 28: } 29:  30: ... 31:  32: } 33: } Now to be fair, I’m not saying there doesn’t exist an organization where some entites may be extremely static and unchanging.  But at best such entities and DAOs will be problematic cases of reuse.  Let’s examine those same tests: Single Responsibility Principle (SRP) – The reasons to change for these classes will be strongly dependent on what the definition of the account is which can change over time and may have multiple influences depending on the number of systems an account can cover. Stable Dependencies Principle (SDP) – This method depends on the data model beneath itself which also is largely dependent on the business definition of an account which can be very inherently unstable. Open-Closed Principle (OCP) – This class is not really closed for modification.  Every time the account definition may change, you’d need to modify this class. Small and Stable Problem Domain – The definition of an account is inherently unstable and in fact may be very large.  What if you are designing a system that aggregates account information from several sources? All-or-None Usage – What if your view of the account encompasses data from 3 different sources but you only care about one of those sources or one piece of data?  Should you have to take the hit of looking up all the other data?  On the other hand, should you have ten different methods returning portions of data in chunks people tend to ask for?  Neither is really a great solution. Cost of Reuse vs. Cost to Recreate – DAOs are really trivial to rewrite, and unless your definition of an account is EXTREMELY stable, the cost to promote, support, and release a reusable account entity and DAO are usually far higher than the cost to recreate as needed. It’s no accident that my case for reuse was a utility class and my case for non-reuse was an entity/DAO.  In general, the smaller and more stable an abstraction is, the higher its level of reuse.  When I became the lead of the Shared Components Committee at my workplace, one of the original goals we looked at satisfying was to find (or create), version, release, and promote a shared library of common utility classes, frameworks, and data access objects.  Now, of course, many of you will point to nHibernate and Entity for the latter, but we were looking at larger, macro collections of data that span multiple data sources of varying types (databases, web services, etc). As we got deeper and deeper in the details of how to manage and release these items, it quickly became apparent that while the case for reuse was typically a slam dunk for utilities and frameworks, the data access objects just didn’t “smell” right.  We ended up having session after session of design meetings to try and find the right way to share these data access components. When someone asked me why it was taking so long to iron out the shared entities, my response was quite simple, “Reuse is hard...”  And that’s when I realized, that while reuse is an awesome goal and we should strive to make code maintainable, often times you end up creating far more work for yourself than necessary by trying to force code to be reusable that inherently isn’t. Think about classes the times you’ve worked in a company where in the design session people fight over the best way to implement a class to make it maximally reusable, extensible, and any other buzzwordable.  Then think about how quickly that design became obsolete.  Many times I set out to do a project and think, “yes, this is the best design, I can extend it easily!” only to find out the business requirements change COMPLETELY in such a way that the design is rendered invalid.  Code, in general, tends to rust and age over time.  As such, writing reusable code can often be difficult and many times ends up being a futile exercise and worse yet, sometimes makes the code harder to maintain because it obfuscates the design in the name of extensibility or reusability. So what do I think are reusable components? Generic Utility classes – these tend to be small classes that assist in a task and have no business context whatsoever. Implementation Abstraction Frameworks – home-grown frameworks that try to isolate changes to third party products you may be depending on (like writing a messaging abstraction layer for publishing/subscribing that is independent of whether you use JMS, MSMQ, etc). Simplification and Uniformity Frameworks – To some extent this is similar to an abstraction framework, but there may be one chosen provider but a development shop mandate to perform certain complex items in a certain way.  Or, perhaps to simplify and dumb-down a complex task for the average developer (such as implementing a particular development-shop’s method of encryption). And what are less reusable? Application and Business Layers – tend to fluctuate a lot as requirements change and new features are added, so tend to be an unstable dependency.  May be reused across applications but also very volatile. Entities and Data Access Layers – these tend to be tuned to the scope of the application, so reusing them can be hard unless the abstract is very stable. So what’s the big lesson?  Reuse is hard.  In fact it’s damn hard.  And much of the time I’m not convinced we should focus too hard on it. If you’re designing a utility or framework, then by all means design it for reuse.  But you most also really set down a good versioning, release, and documentation process to maximize your chances.  For anything else, design it to be maintainable and extendable, but don’t waste the effort on reusability for something that most likely will be obsolete in a year or two anyway.

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  • "interface not found" in WCF Moniker without registration for excel

    - by tbischel
    I'm trying to connect excel to a WCF service, but I can't seem to get even a trivial case to work... I get an Invalid Syntax error when I try and create the proxy in excel. I've attached the visual studio debugger to excel, and get that the real error is "interface not found". I know the service works because the test client created by visual studio is ok... so the problem is in the VBA moniker string. I'm hoping to find one of two things: 1) a correction to my moniker string that will make this work, or 2) an existing sample project to download that has the source for both the host and client that does work. Here is the code for my VBA client: Dim addr As String addr = "service:mexAddress=net.tcp://localhost:7891/Test/WcfService1/Service1/mex, " addr = addr + "address=net.tcp://localhost:7891/Test/WcfService1/Service1/, " addr = addr + "contract=IService1, contractNamespace=http://tempuri.org, " addr = addr + "binding=NetTcpBinding_IService1, bindingNamespace=""http://tempuri.org""" MsgBox (addr) Dim service1 As Object Set service1 = GetObject(addr) MsgBox service1.Test(12) I have the following service: [ServiceContract] public interface IService1 { [OperationContract] string GetData(int value); } public class Service1 : IService1 { public string GetData(int value) { return string.Format("You entered: {0}", value); } } It has the following config file: <?xml version="1.0" encoding="utf-8" ?> <configuration> <system.web> <compilation debug="true" /> </system.web> <!-- When deploying the service library project, the content of the config file must be added to the host's app.config file. System.Configuration does not support config files for libraries. --> <system.serviceModel> <services> <service behaviorConfiguration="WcfService1.Service1Behavior" name="WcfService1.Service1"> <endpoint address="" binding="netTcpBinding" bindingConfiguration="" contract="WcfService1.IService1"> <identity> <dns value="localhost" /> </identity> </endpoint> <endpoint address="mex" binding="mexTcpBinding" bindingConfiguration="" contract="IMetadataExchange" /> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:7891/Test/WcfService1/Service1/" /> </baseAddresses> </host> </service> </services> <behaviors> <serviceBehaviors> <behavior name="WcfService1.Service1Behavior"> <serviceMetadata httpGetEnabled="false" /> <serviceDebug includeExceptionDetailInFaults="false" /> </behavior> </serviceBehaviors> </behaviors> </system.serviceModel> </configuration>

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  • C#/.NET Little Wonders: The Nullable static class

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Today we’re going to look at an interesting Little Wonder that can be used to mitigate what could be considered a Little Pitfall.  The Little Wonder we’ll be examining is the System.Nullable static class.  No, not the System.Nullable<T> class, but a static helper class that has one useful method in particular that we will examine… but first, let’s look at the Little Pitfall that makes this wonder so useful. Little Pitfall: Comparing nullable value types using <, >, <=, >= Examine this piece of code, without examining it too deeply, what’s your gut reaction as to the result? 1: int? x = null; 2:  3: if (x < 100) 4: { 5: Console.WriteLine("True, {0} is less than 100.", 6: x.HasValue ? x.ToString() : "null"); 7: } 8: else 9: { 10: Console.WriteLine("False, {0} is NOT less than 100.", 11: x.HasValue ? x.ToString() : "null"); 12: } Your gut would be to say true right?  It would seem to make sense that a null integer is less than the integer constant 100.  But the result is actually false!  The null value is not less than 100 according to the less-than operator. It looks even more outrageous when you consider this also evaluates to false: 1: int? x = null; 2:  3: if (x < int.MaxValue) 4: { 5: // ... 6: } So, are we saying that null is less than every valid int value?  If that were true, null should be less than int.MinValue, right?  Well… no: 1: int? x = null; 2:  3: // um... hold on here, x is NOT less than min value? 4: if (x < int.MinValue) 5: { 6: // ... 7: } So what’s going on here?  If we use greater than instead of less than, we see the same little dilemma: 1: int? x = null; 2:  3: // once again, null is not greater than anything either... 4: if (x > int.MinValue) 5: { 6: // ... 7: } It turns out that four of the comparison operators (<, <=, >, >=) are designed to return false anytime at least one of the arguments is null when comparing System.Nullable wrapped types that expose the comparison operators (short, int, float, double, DateTime, TimeSpan, etc.).  What’s even odder is that even though the two equality operators (== and !=) work correctly, >= and <= have the same issue as < and > and return false if both System.Nullable wrapped operator comparable types are null! 1: DateTime? x = null; 2: DateTime? y = null; 3:  4: if (x <= y) 5: { 6: Console.WriteLine("You'd think this is true, since both are null, but it's not."); 7: } 8: else 9: { 10: Console.WriteLine("It's false because <=, <, >, >= don't work on null."); 11: } To make matters even more confusing, take for example your usual check to see if something is less than, greater to, or equal: 1: int? x = null; 2: int? y = 100; 3:  4: if (x < y) 5: { 6: Console.WriteLine("X is less than Y"); 7: } 8: else if (x > y) 9: { 10: Console.WriteLine("X is greater than Y"); 11: } 12: else 13: { 14: // We fall into the "equals" assumption, but clearly null != 100! 15: Console.WriteLine("X is equal to Y"); 16: } Yes, this code outputs “X is equal to Y” because both the less-than and greater-than operators return false when a Nullable wrapped operator comparable type is null.  This violates a lot of our assumptions because we assume is something is not less than something, and it’s not greater than something, it must be equal.  So keep in mind, that the only two comparison operators that work on Nullable wrapped types where at least one is null are the equals (==) and not equals (!=) operators: 1: int? x = null; 2: int? y = 100; 3:  4: if (x == y) 5: { 6: Console.WriteLine("False, x is null, y is not."); 7: } 8:  9: if (x != y) 10: { 11: Console.WriteLine("True, x is null, y is not."); 12: } Solution: The Nullable static class So we’ve seen that <, <=, >, and >= have some interesting and perhaps unexpected behaviors that can trip up a novice developer who isn’t expecting the kinks that System.Nullable<T> types with comparison operators can throw.  How can we easily mitigate this? Well, obviously, you could do null checks before each check, but that starts to get ugly: 1: if (x.HasValue) 2: { 3: if (y.HasValue) 4: { 5: if (x < y) 6: { 7: Console.WriteLine("x < y"); 8: } 9: else if (x > y) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } 17: } 18: else 19: { 20: Console.WriteLine("x > y because y is null and x isn't"); 21: } 22: } 23: else if (y.HasValue) 24: { 25: Console.WriteLine("x < y because x is null and y isn't"); 26: } 27: else 28: { 29: Console.WriteLine("x == y because both are null"); 30: } Yes, we could probably simplify this logic a bit, but it’s still horrendous!  So what do we do if we want to consider null less than everything and be able to properly compare Nullable<T> wrapped value types? The key is the System.Nullable static class.  This class is a companion class to the System.Nullable<T> class and allows you to use a few helper methods for Nullable<T> wrapped types, including a static Compare<T>() method of the. What’s so big about the static Compare<T>() method?  It implements an IComparer compatible comparison on Nullable<T> types.  Why do we care?  Well, if you look at the MSDN description for how IComparer works, you’ll read: Comparing null with any type is allowed and does not generate an exception when using IComparable. When sorting, null is considered to be less than any other object. This is what we probably want!  We want null to be less than everything!  So now we can change our logic to use the Nullable.Compare<T>() static method: 1: int? x = null; 2: int? y = 100; 3:  4: if (Nullable.Compare(x, y) < 0) 5: { 6: // Yes! x is null, y is not, so x is less than y according to Compare(). 7: Console.WriteLine("x < y"); 8: } 9: else if (Nullable.Compare(x, y) > 0) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } Summary So, when doing math comparisons between two numeric values where one of them may be a null Nullable<T>, consider using the System.Nullable.Compare<T>() method instead of the comparison operators.  It will treat null less than any value, and will avoid logic consistency problems when relying on < returning false to indicate >= is true and so on. Tweet   Technorati Tags: C#,C-Sharp,.NET,Little Wonders,Little Pitfalls,Nulalble

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  • C#/.NET Little Wonders: Use Cast() and TypeOf() to Change Sequence Type

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. We’ve seen how the Select() extension method lets you project a sequence from one type to a new type which is handy for getting just parts of items, or building new items.  But what happens when the items in the sequence are already the type you want, but the sequence itself is typed to an interface or super-type instead of the sub-type you need? For example, you may have a sequence of Rectangle stored in an IEnumerable<Shape> and want to consider it an IEnumerable<Rectangle> sequence instead.  Today we’ll look at two handy extension methods, Cast<TResult>() and OfType<TResult>() which help you with this task. Cast<TResult>() – Attempt to cast all items to type TResult So, the first thing we can do would be to attempt to create a sequence of TResult from every item in the source sequence.  Typically we’d do this if we had an IEnumerable<T> where we knew that every item was actually a TResult where TResult inherits/implements T. For example, assume the typical Shape example classes: 1: // abstract base class 2: public abstract class Shape { } 3:  4: // a basic rectangle 5: public class Rectangle : Shape 6: { 7: public int Widtgh { get; set; } 8: public int Height { get; set; } 9: } And let’s assume we have a sequence of Shape where every Shape is a Rectangle… 1: var shapes = new List<Shape> 2: { 3: new Rectangle { Width = 3, Height = 5 }, 4: new Rectangle { Width = 10, Height = 13 }, 5: // ... 6: }; To get the sequence of Shape as a sequence of Rectangle, of course, we could use a Select() clause, such as: 1: // select each Shape, cast it to Rectangle 2: var rectangles = shapes 3: .Select(s => (Rectangle)s) 4: .ToList(); But that’s a bit verbose, and fortunately there is already a facility built in and ready to use in the form of the Cast<TResult>() extension method: 1: // cast each item to Rectangle and store in a List<Rectangle> 2: var rectangles = shapes 3: .Cast<Rectangle>() 4: .ToList(); However, we should note that if anything in the list cannot be cast to a Rectangle, you will get an InvalidCastException thrown at runtime.  Thus, if our Shape sequence had a Circle in it, the call to Cast<Rectangle>() would have failed.  As such, you should only do this when you are reasonably sure of what the sequence actually contains (or are willing to handle an exception if you’re wrong). Another handy use of Cast<TResult>() is using it to convert an IEnumerable to an IEnumerable<T>.  If you look at the signature, you’ll see that the Cast<TResult>() extension method actually extends the older, object-based IEnumerable interface instead of the newer, generic IEnumerable<T>.  This is your gateway method for being able to use LINQ on older, non-generic sequences.  For example, consider the following: 1: // the older, non-generic collections are sequence of object 2: var shapes = new ArrayList 3: { 4: new Rectangle { Width = 3, Height = 13 }, 5: new Rectangle { Width = 10, Height = 20 }, 6: // ... 7: }; Since this is an older, object based collection, we cannot use the LINQ extension methods on it directly.  For example, if I wanted to query the Shape sequence for only those Rectangles whose Width is > 5, I can’t do this: 1: // compiler error, Where() operates on IEnumerable<T>, not IEnumerable 2: var bigRectangles = shapes.Where(r => r.Width > 5); However, I can use Cast<Rectangle>() to treat my ArrayList as an IEnumerable<Rectangle> and then do the query! 1: // ah, that’s better! 2: var bigRectangles = shapes.Cast<Rectangle>().Where(r => r.Width > 5); Or, if you prefer, in LINQ query expression syntax: 1: var bigRectangles = from s in shapes.Cast<Rectangle>() 2: where s.Width > 5 3: select s; One quick warning: Cast<TResult>() only attempts to cast, it won’t perform a cast conversion.  That is, consider this: 1: var intList = new List<int> { 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 }; 2:  3: // casting ints to longs, this should work, right? 4: var asLong = intList.Cast<long>().ToList(); Will the code above work?  No, you’ll get a InvalidCastException. Remember that Cast<TResult>() is an extension of IEnumerable, thus it is a sequence of object, which means that it will box every int as an object as it enumerates over it, and there is no cast conversion from object to long, and thus the cast fails.  In other words, a cast from int to long will succeed because there is a conversion from int to long.  But a cast from int to object to long will not, because you can only unbox an item by casting it to its exact type. For more information on why cast-converting boxed values doesn’t work, see this post on The Dangers of Casting Boxed Values (here). OfType<TResult>() – Filter sequence to only items of type TResult So, we’ve seen how we can use Cast<TResult>() to change the type of our sequence, when we expect all the items of the sequence to be of a specific type.  But what do we do when a sequence contains many different types, and we are only concerned with a subset of a given type? For example, what if a sequence of Shape contains Rectangle and Circle instances, and we just want to select all of the Rectangle instances?  Well, let’s say we had this sequence of Shape: 1: var shapes = new List<Shape> 2: { 3: new Rectangle { Width = 3, Height = 5 }, 4: new Rectangle { Width = 10, Height = 13 }, 5: new Circle { Radius = 10 }, 6: new Square { Side = 13 }, 7: // ... 8: }; Well, we could get the rectangles using Select(), like: 1: var onlyRectangles = shapes.Where(s => s is Rectangle).ToList(); But fortunately, an easier way has already been written for us in the form of the OfType<T>() extension method: 1: // returns only a sequence of the shapes that are Rectangles 2: var onlyRectangles = shapes.OfType<Rectangle>().ToList(); Now we have a sequence of only the Rectangles in the original sequence, we can also use this to chain other queries that depend on Rectangles, such as: 1: // select only Rectangles, then filter to only those more than 2: // 5 units wide... 3: var onlyBigRectangles = shapes.OfType<Rectangle>() 4: .Where(r => r.Width > 5) 5: .ToList(); The OfType<Rectangle>() will filter the sequence to only the items that are of type Rectangle (or a subclass of it), and that results in an IEnumerable<Rectangle>, we can then apply the other LINQ extension methods to query that list further. Just as Cast<TResult>() is an extension method on IEnumerable (and not IEnumerable<T>), the same is true for OfType<T>().  This means that you can use OfType<TResult>() on object-based collections as well. For example, given an ArrayList containing Shapes, as below: 1: // object-based collections are a sequence of object 2: var shapes = new ArrayList 3: { 4: new Rectangle { Width = 3, Height = 5 }, 5: new Rectangle { Width = 10, Height = 13 }, 6: new Circle { Radius = 10 }, 7: new Square { Side = 13 }, 8: // ... 9: }; We can use OfType<Rectangle> to filter the sequence to only Rectangle items (and subclasses), and then chain other LINQ expressions, since we will then be of type IEnumerable<Rectangle>: 1: // OfType() converts the sequence of object to a new sequence 2: // containing only Rectangle or sub-types of Rectangle. 3: var onlyBigRectangles = shapes.OfType<Rectangle>() 4: .Where(r => r.Width > 5) 5: .ToList(); Summary So now we’ve seen two different ways to get a sequence of a superclass or interface down to a more specific sequence of a subclass or implementation.  The Cast<TResult>() method casts every item in the source sequence to type TResult, and the OfType<TResult>() method selects only those items in the source sequence that are of type TResult. You can use these to downcast sequences, or adapt older types and sequences that only implement IEnumerable (such as DataTable, ArrayList, etc.). Technorati Tags: C#,CSharp,.NET,LINQ,Little Wonders,TypeOf,Cast,IEnumerable<T>

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  • Overriding Object.Equals() instance method in C#; now Code Analysis / FxCop warning CA2218: "should

    - by Chris W. Rea
    I've got a complex class in my C# project on which I want to be able to do equality tests. It is not a trivial class; it contains a variety of scalar properties as well as references to other objects and collections (e.g. IDictionary). For what it's worth, my class is sealed. To enable a performance optimization elsewhere in my system (an optimization that avoids a costly network round-trip), I need to be able to compare instances of these objects to each other for equality – other than the built-in reference equality – and so I'm overriding the Object.Equals() instance method. However, now that I've done that, Visual Studio 2008's Code Analysis a.k.a. FxCop, which I keep enabled by default, is raising the following warning: warning : CA2218 : Microsoft.Usage : Since 'MySuperDuperClass' redefines Equals, it should also redefine GetHashCode. I think I understand the rationale for this warning: If I am going to be using such objects as the key in a collection, the hash code is important. i.e. see this question. However, I am not going to be using these objects as the key in a collection. Ever. Feeling justified to suppress the warning, I looked up code CA2218 in the MSDN documentation to get the full name of the warning so I could apply a SuppressMessage attribute to my class as follows: [SuppressMessage("Microsoft.Naming", "CA2218:OverrideGetHashCodeOnOverridingEquals", Justification="This class is not to be used as key in a hashtable.")] However, while reading further, I noticed the following: How to Fix Violations To fix a violation of this rule, provide an implementation of GetHashCode. For a pair of objects of the same type, you must ensure that the implementation returns the same value if your implementation of Equals returns true for the pair. When to Suppress Warnings ----- Do not suppress a warning from this rule. [arrow & emphasis mine] So, I'd like to know: Why shouldn't I suppress this warning as I was planning to? Doesn't my case warrant suppression? I don't want to code up an implementation of GetHashCode() for this object that will never get called, since my object will never be the key in a collection. If I wanted to be pedantic, instead of suppressing, would it be more reasonable for me to override GetHashCode() with an implementation that throws a NotImplementedException? Update: I just looked this subject up again in Bill Wagner's good book Effective C#, and he states in "Item 10: Understand the Pitfalls of GetHashCode()": If you're defining a type that won't ever be used as the key in a container, this won't matter. Types that represent window controls, web page controls, or database connections are unlikely to be used as keys in a collection. In those cases, do nothing. All reference types will have a hash code that is correct, even if it is very inefficient. [...] In most types that you create, the best approach is to avoid the existence of GetHashCode() entirely. ... that's where I originally got this idea that I need not be concerned about GetHashCode() always.

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  • C#: Handling Notifications: inheritance, events, or delegates?

    - by James Michael Hare
    Often times as developers we have to design a class where we get notification when certain things happen. In older object-oriented code this would often be implemented by overriding methods -- with events, delegates, and interfaces, however, we have far more elegant options. So, when should you use each of these methods and what are their strengths and weaknesses? Now, for the purposes of this article when I say notification, I'm just talking about ways for a class to let a user know that something has occurred. This can be through any programmatic means such as inheritance, events, delegates, etc. So let's build some context. I'm sitting here thinking about a provider neutral messaging layer for the place I work, and I got to the point where I needed to design the message subscriber which will receive messages from the message bus. Basically, what we want is to be able to create a message listener and have it be called whenever a new message arrives. Now, back before the flood we would have done this via inheritance and an abstract class: 1:  2: // using inheritance - omitting argument null checks and halt logic 3: public abstract class MessageListener 4: { 5: private ISubscriber _subscriber; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber) 11: { 12: _subscriber = subscriber; 13: _messageThread = new Thread(MessageLoop); 14: _messageThread.Start(); 15: } 16:  17: // user will override this to process their messages 18: protected abstract void OnMessageReceived(Message msg); 19:  20: // handle the looping in the thread 21: private void MessageLoop() 22: { 23: while(!_isHalted) 24: { 25: // as long as processing, wait 1 second for message 26: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 27: if(msg != null) 28: { 29: OnMessageReceived(msg); 30: } 31: } 32: } 33: ... 34: } It seems so odd to write this kind of code now. Does it feel odd to you? Maybe it's just because I've gotten so used to delegation that I really don't like the feel of this. To me it is akin to saying that if I want to drive my car I need to derive a new instance of it just to put myself in the driver's seat. And yet, unquestionably, five years ago I would have probably written the code as you see above. To me, inheritance is a flawed approach for notifications due to several reasons: Inheritance is one of the HIGHEST forms of coupling. You can't seal the listener class because it depends on sub-classing to work. Because C# does not allow multiple-inheritance, I've spent my one inheritance implementing this class. Every time you need to listen to a bus, you have to derive a class which leads to lots of trivial sub-classes. The act of consuming a message should be a separate responsibility than the act of listening for a message (SRP). Inheritance is such a strong statement (this IS-A that) that it should only be used in building type hierarchies and not for overriding use-specific behaviors and notifications. Chances are, if a class needs to be inherited to be used, it most likely is not designed as well as it could be in today's modern programming languages. So lets look at the other tools available to us for getting notified instead. Here's a few other choices to consider. Have the listener expose a MessageReceived event. Have the listener accept a new IMessageHandler interface instance. Have the listener accept an Action<Message> delegate. Really, all of these are different forms of delegation. Now, .NET events are a bit heavier than the other types of delegates in terms of run-time execution, but they are a great way to allow others using your class to subscribe to your events: 1: // using event - ommiting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private bool _isHalted = false; 6: private Thread _messageThread; 7:  8: // assign the subscriber and start the messaging loop 9: public MessageListener(ISubscriber subscriber) 10: { 11: _subscriber = subscriber; 12: _messageThread = new Thread(MessageLoop); 13: _messageThread.Start(); 14: } 15:  16: // user will override this to process their messages 17: public event Action<Message> MessageReceived; 18:  19: // handle the looping in the thread 20: private void MessageLoop() 21: { 22: while(!_isHalted) 23: { 24: // as long as processing, wait 1 second for message 25: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 26: if(msg != null && MessageReceived != null) 27: { 28: MessageReceived(msg); 29: } 30: } 31: } 32: } Note, now we can seal the class to avoid changes and the user just needs to provide a message handling method: 1: theListener.MessageReceived += CustomReceiveMethod; However, personally I don't think events hold up as well in this case because events are largely optional. To me, what is the point of a listener if you create one with no event listeners? So in my mind, use events when handling the notification is optional. So how about the delegation via interface? I personally like this method quite a bit. Basically what it does is similar to inheritance method mentioned first, but better because it makes it easy to split the part of the class that doesn't change (the base listener behavior) from the part that does change (the user-specified action after receiving a message). So assuming we had an interface like: 1: public interface IMessageHandler 2: { 3: void OnMessageReceived(Message receivedMessage); 4: } Our listener would look like this: 1: // using delegation via interface - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private IMessageHandler _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler.OnMessageReceived(msg); 28: } 29: } 30: } 31: } And they would call it by creating a class that implements IMessageHandler and pass that instance into the constructor of the listener. I like that this alleviates the issues of inheritance and essentially forces you to provide a handler (as opposed to events) on construction. Well, this is good, but personally I think we could go one step further. While I like this better than events or inheritance, it still forces you to implement a specific method name. What if that name collides? Furthermore if you have lots of these you end up either with large classes inheriting multiple interfaces to implement one method, or lots of small classes. Also, if you had one class that wanted to manage messages from two different subscribers differently, it wouldn't be able to because the interface can't be overloaded. This brings me to using delegates directly. In general, every time I think about creating an interface for something, and if that interface contains only one method, I start thinking a delegate is a better approach. Now, that said delegates don't accomplish everything an interface can. Obviously having the interface allows you to refer to the classes that implement the interface which can be very handy. In this case, though, really all you want is a method to handle the messages. So let's look at a method delegate: 1: // using delegation via delegate - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler(msg); 28: } 29: } 30: } 31: } Here the MessageListener now takes an Action<Message>.  For those of you unfamiliar with the pre-defined delegate types in .NET, that is a method with the signature: void SomeMethodName(Message). The great thing about delegates is it gives you a lot of power. You could create an anonymous delegate, a lambda, or specify any other method as long as it satisfies the Action<Message> signature. This way, you don't need to define an arbitrary helper class or name the method a specific thing. Incidentally, we could combine both the interface and delegate approach to allow maximum flexibility. Doing this, the user could either pass in a delegate, or specify a delegate interface: 1: // using delegation - give users choice of interface or delegate 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // passes the interface method as a delegate using method group 19: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 20: : this(subscriber, handler.OnMessageReceived) 21: { 22: } 23:  24: // handle the looping in the thread 25: private void MessageLoop() 26: { 27: while(!_isHalted) 28: { 29: // as long as processing, wait 1 second for message 30: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 31: if(msg != null) 32: { 33: _handler(msg); 34: } 35: } 36: } 37: } } This is the method I tend to prefer because it allows the user of the class to choose which method works best for them. You may be curious about the actual performance of these different methods. 1: Enter iterations: 2: 1000000 3:  4: Inheritance took 4 ms. 5: Events took 7 ms. 6: Interface delegation took 4 ms. 7: Lambda delegate took 5 ms. Before you get too caught up in the numbers, however, keep in mind that this is performance over over 1,000,000 iterations. Since they are all < 10 ms which boils down to fractions of a micro-second per iteration so really any of them are a fine choice performance wise. As such, I think the choice of what to do really boils down to what you're trying to do. Here's my guidelines: Inheritance should be used only when defining a collection of related types with implementation specific behaviors, it should not be used as a hook for users to add their own functionality. Events should be used when subscription is optional or multi-cast is desired. Interface delegation should be used when you wish to refer to implementing classes by the interface type or if the type requires several methods to be implemented. Delegate method delegation should be used when you only need to provide one method and do not need to refer to implementers by the interface name.

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  • CodePlex Daily Summary for Wednesday, December 22, 2010

    CodePlex Daily Summary for Wednesday, December 22, 2010Popular ReleasesTibiaPinger: TibiaPinger v1.0: TibiaPinger v1.0Media Companion: Media Companion 3.400: Extract the entire archive to a folder which has user access rights, eg desktop, documents etc. A manual is included to get you startedPackage that minifies and combines JavaScript and CSS files: Release 1.1: Bug fixes. The package now correctly handles inlined images and image urls in CSS files surrounded by quotes. CombineAndMinify can now be used in conjunction with Microsoft's Sprite and Image Optimization Framework. That framework combines several small images into one, reducing overall load times.Multicore Task Framework: MTF 1.0.1: Release 1.0.1 of Multicore Task Framework.SQL Monitor - tracking sql server activities: SQL Monitor 3.0 alpha 7: 1. added script save/load in user query window 2. fixed problem with connection dialog when choosing windows auth but still ask for user name 3. auto open user table when double click one table node 4. improved alert message, added log only methodOpen NFe: Open NFe 2.0 (Beta): Última versão antes da versão final a ser lançada nos próximos dias.EnhSim: EnhSim 2.2.6 ALPHA: 2.2.6 ALPHAThis release supports WoW patch 4.03a at level 85 To use this release, you must have the Microsoft Visual C++ 2010 Redistributable Package installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=A7B7A05E-6DE6-4D3A-A423-37BF0912DB84 To use the GUI you must have the .NET 4.0 Framework installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992 - Fixing up some r...LINQ to Twitter: LINQ to Twitter Beta v2.0.18: Silverlight, OAuth, 100% Twitter API coverage, streaming, extensibility via Raw Queries, and added documentation. Bug fixes.ASP.NET MVC Project Awesome (jQuery Ajax helpers): 1.4.3: Helpers (controls) that you can use to build highly responsive and interactive Ajax-enabled Web applications. These helpers include Autocomplete, AjaxDropdown, Lookup, Confirm Dialog, Popup Form, Popup and Pager new stuff: Improvements for confirm, popup, popup form RenderView controller extension the user experience for crud in live demo has been substantially improved + added search all the features are shown in the live demoGanttPlanner: GanttPlanner V1.0: GanttPlanner V1.0 include GanttPlanner.dll and also a Demo application.N2 CMS: 2.1 release candidate 3: * Web platform installer support available N2 is a lightweight CMS framework for ASP.NET. It helps you build great web sites that anyone can update. Major Changes Support for auto-implemented properties ({get;set;}, based on contribution by And Poulsen) A bunch of bugs were fixed File manager improvements (multiple file upload, resize images to fit) New image gallery Infinite scroll paging on news Content templates First time with N2? Try the demo site Download one of the templ...TweetSharp: TweetSharp v2.0.0.0 - Preview 6: Documentation for this release may be found at http://tweetsharp.codeplex.com/wikipage?title=UserGuide&referringTitle=Documentation. Note: This code is currently preview quality. Preview 6 ChangesMaintenance release with user reported fixes Preview 5 ChangesMaintenance release with user reported fixes Preview 4 ChangesReintroduced fluent interface support via satellite assembly Added entities support, entity segmentation, and ITweetable/ITweeter interfaces for client development Numer...Team Foundation Server Administration Tool: 2.1: TFS Administration Tool 2.1, is the first version of the TFS Administration Tool which is built on top of the Team Foundation Server 2010 object model. TFS Administration Tool 2.1 can be installed on machines that are running either Team Explorer 2010, or Team Foundation Server 2010.SubtitleTools: SubtitleTools 1.3: - Added .srt FileAssociation & Win7 ShowRecentCategory feature. - Applied UnifiedYeKe to fix Persian search problems. - Reduced file size of Persian subtitles for uploading @OSDB.Facebook C# SDK: 4.1.0: - Lots of bug fixes - Removed Dynamic Runtime Language dependencies from non-dynamic platforms. - Samples included in release for ASP.NET, MVC, Silverlight, Windows Phone 7, WPF, WinForms, and one Visual Basic Sample - Changed internal serialization to use Json.net - BREAKING CHANGE: Canvas Session is no longer support. Use Signed Request instead. Canvas Session has been deprecated by Facebook. - BREAKING CHANGE: Some renames and changes with Authorizer, CanvasAuthorizer, and Authorization ac...NuGet: NuGet 1.0 build 11217.102: Note: this release is slightly newer than RC1, and fixes a couple issues relating to updating packages to newer versions. NuGet is a free, open source developer focused package management system for the .NET platform intent on simplifying the process of incorporating third party libraries into a .NET application during development. This release is a Visual Studio 2010 extension and contains the the Package Manager Console and the Add Package Dialog. This new build targets the newer feed (h...WCF Community Site: WCF Web APIs 10.12.17: Welcome to the second release of WCF Web APIs on codeplex Here is what is new in this release. WCF Support for jQuery - create WCF web services that are easy to consume from JavaScript clients, in particular jQuery. Better support for using JsonValue as dynamic Support for JsonValue change notification events for databinding and other purposes Support for going between JsonValue and CLR types WCF HTTP - create HTTP / REST based web services. This is a minor release which contains fixe...LiveChat Starter Kit: LCSK v1.0: This is a working version of the LCSK for Visual Studio 2010, ASP.NET MVC 3 (using Razor View Engine). this is still provider based (with 1 provider Sql) and this is still using WebService and Windows Forms operator console. The solution is cleaner, with an installer to create tables etc. You can also install it via nuget (Install-Package lcsk) Let me know your feedbackOrchard Project: Orchard 0.9: Orchard Release Notes Build: 0.9.253 Published: 12/16/2010 How to Install OrchardTo install the Orchard tech preview using Web PI, follow these instructions: http://www.orchardproject.net/docs/Installing-Orchard-Using-Web-PI.ashx Web PI will detect your hardware environment and install the application. --OR-- Alternatively, to install the release manually, download the Orchard.Web.0.9.253.zip file. The zip contents are pre-built and ready-to-run. Simply extract the contents of the Orch...DotSpatial: DotSpatial 12-15-2010: This release contains a few minor bug fixes and hopefully the GDAL libraries for the 3.5 x86 build actually built to the correct directory this time.New Projects1102 Puc enigami: noitpircsedaarron: personalALDX Organizer: C# .NET desktop application meant to help a store manager in running the store.Battle.Net Library: This is a collaborate Blizzard Battle.net api. Currently working on fetching data from the Armory.BBSolution: BBSolution cmsBitlyTweeter: A Windows Live Writer plugin designed to hook up to your bit.ly account and automatically send tweets after you publish a blog post with the URL shortened by your account.Chat World: chat privado sin reestricciones de ningun tipo aplicacion cliente servidor cliente que te permite crear tus propias salas y categorias de chat sin ninguna reestriccion desarrollado en Net 4.0 lenguaje c#Creating Databound jQuery plugins for ASP.NET: Using asp.net to create a dynamic webservice to support the jQuery jqGrid control as a databound server control. Developed in C# and Javascript. Designed to remove excessive extra coding to add rows to gridview control. Short time to fully developed control.DriverStore Explorer [RAPR]: DriverStoreExplorer GUI makes it easier to deal with Windows Vista / Windows 7 driver store. Supported operations include enumeration, adding a driver package (stage), adding & installing, deletion, as well as force deletion from the driver store. GCTF: Desafio .NET Realizado na FACISAGonte.Utilities: Gonte.Utilites Provides general utilities such as - Reflection helpers - Validation framworkLincoln Wood: An evolutionary implementation of the next gen Lincoln Wood Community environment using MVC2 and other good stuff.M4N1: M4N1 its a MDA arquitecture that tries to enable Model Development for anyone! Its written an Java and the IDE its an Eclipse RCP application.MasterGuitarReader: guitarmd5util: MD5 checksum util for developersMP3Tunes Windows Locker Player: Connect to your MP3Tunes locker from a win7/vista/xp computer.MVC Installer: The MVC Installer is a small, pluggable assembly that you add to any new ASP.NET MVC 2 project to easily install your database and Membership system with Roles and Users.new1: new1new1new1new1new1O(∩_∩)O: .SharePoint 2007 Add Ons: The goal of this project is to develop a set of add ons for SharePoint 2007.SharePoint Power Pack: The SharePoint Power Pack consists of several features to enhance core functionality and change the user experience of the SharePoint GUI.Silverlight Code Camp Reference Implementation: Silverlight Code Camp Website Australia 2011. Technology: C#, Silverlight, Asp.Net MVC, jQuery Features: CodeCamp Sessions, Location Map, User Voting, Registration (via EventBrite), Down Level Experience, Mobile Browsers friendly CSS Silverlight Sockets Sample: Trivial but complete sample for doing SL sockets. There is an SL project and a console socket server handling 943rd (SL policy) port and 4505th (for arbitrary data communication).SMILE Media Content Creator: A WinForm GUI for generating SMILE Media ContentSocialPad: socialpadSpits: Comment SNS for files: A sns like comment system. can make comments with your very local files StarTrooper: ????,??MSDN Webcast ???,???VB A game, reference MSDN Webcast produced by the language is Visual Basic http://www.msdnwebcast.com.cn/CourseSeries.aspx?id=58Text Data File Manipulator: Manipulate text data files: convert separators, transpose data. For some reason I couldn't find a simple tool for window to transpose my large data files so I wrote this tiny tool. uLogin: uLogin version 1.0.1 provides Member Login functionality for Umbraco-powered Web sites. uLogin version 1.0.1 was developed and tested for Umbraco version 4.5.2 with ASP.net version 4.Windows Media Player GNTP Plugin: WMP-GNTP allows Windows Media Player to tell Growl for Windows when a song has changed, so you'll no longer have to open Windows Media Player to tell when a song has changed. It's developed in C++/ATL.WorldBuilder: This Application will help XNA developers create game maps and easily implement them into their games. This includes both 2D maps and 3D Terrain maps.

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  • C#/.NET Little Wonders: Skip() and Take()

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. I’ve covered many valuable methods from System.Linq class library before, so you already know it’s packed with extension-method goodness.  Today I’d like to cover two small families I’ve neglected to mention before: Skip() and Take().  While these methods seem so simple, they are an easy way to create sub-sequences for IEnumerable<T>, much the way GetRange() creates sub-lists for List<T>. Skip() and SkipWhile() The Skip() family of methods is used to ignore items in a sequence until either a certain number are passed, or until a certain condition becomes false.  This makes the methods great for starting a sequence at a point possibly other than the first item of the original sequence.   The Skip() family of methods contains the following methods (shown below in extension method syntax): Skip(int count) Ignores the specified number of items and returns a sequence starting at the item after the last skipped item (if any).  SkipWhile(Func<T, bool> predicate) Ignores items as long as the predicate returns true and returns a sequence starting with the first item to invalidate the predicate (if any).  SkipWhile(Func<T, int, bool> predicate) Same as above, but passes not only the item itself to the predicate, but also the index of the item.  For example: 1: var list = new[] { 3.14, 2.72, 42.0, 9.9, 13.0, 101.0 }; 2:  3: // sequence contains { 2.72, 42.0, 9.9, 13.0, 101.0 } 4: var afterSecond = list.Skip(1); 5: Console.WriteLine(string.Join(", ", afterSecond)); 6:  7: // sequence contains { 42.0, 9.9, 13.0, 101.0 } 8: var afterFirstDoubleDigit = list.SkipWhile(v => v < 10.0); 9: Console.WriteLine(string.Join(", ", afterFirstDoubleDigit)); Note that the SkipWhile() stops skipping at the first item that returns false and returns from there to the rest of the sequence, even if further items in that sequence also would satisfy the predicate (otherwise, you’d probably be using Where() instead, of course). If you do use the form of SkipWhile() which also passes an index into the predicate, then you should keep in mind that this is the index of the item in the sequence you are calling SkipWhile() from, not the index in the original collection.  That is, consider the following: 1: var list = new[] { 1.0, 1.1, 1.2, 2.2, 2.3, 2.4 }; 2:  3: // Get all items < 10, then 4: var whatAmI = list 5: .Skip(2) 6: .SkipWhile((i, x) => i > x); For this example the result above is 2.4, and not 1.2, 2.2, 2.3, 2.4 as some might expect.  The key is knowing what the index is that’s passed to the predicate in SkipWhile().  In the code above, because Skip(2) skips 1.0 and 1.1, the sequence passed to SkipWhile() begins at 1.2 and thus it considers the “index” of 1.2 to be 0 and not 2.  This same logic applies when using any of the extension methods that have an overload that allows you to pass an index into the delegate, such as SkipWhile(), TakeWhile(), Select(), Where(), etc.  It should also be noted, that it’s fine to Skip() more items than exist in the sequence (an empty sequence is the result), or even to Skip(0) which results in the full sequence.  So why would it ever be useful to return Skip(0) deliberately?  One reason might be to return a List<T> as an immutable sequence.  Consider this class: 1: public class MyClass 2: { 3: private List<int> _myList = new List<int>(); 4:  5: // works on surface, but one can cast back to List<int> and mutate the original... 6: public IEnumerable<int> OneWay 7: { 8: get { return _myList; } 9: } 10:  11: // works, but still has Add() etc which throw at runtime if accidentally called 12: public ReadOnlyCollection<int> AnotherWay 13: { 14: get { return new ReadOnlyCollection<int>(_myList); } 15: } 16:  17: // immutable, can't be cast back to List<int>, doesn't have methods that throw at runtime 18: public IEnumerable<int> YetAnotherWay 19: { 20: get { return _myList.Skip(0); } 21: } 22: } This code snippet shows three (among many) ways to return an internal sequence in varying levels of immutability.  Obviously if you just try to return as IEnumerable<T> without doing anything more, there’s always the danger the caller could cast back to List<T> and mutate your internal structure.  You could also return a ReadOnlyCollection<T>, but this still has the mutating methods, they just throw at runtime when called instead of giving compiler errors.  Finally, you can return the internal list as a sequence using Skip(0) which skips no items and just runs an iterator through the list.  The result is an iterator, which cannot be cast back to List<T>.  Of course, there’s many ways to do this (including just cloning the list, etc.) but the point is it illustrates a potential use of using an explicit Skip(0). Take() and TakeWhile() The Take() and TakeWhile() methods can be though of as somewhat of the inverse of Skip() and SkipWhile().  That is, while Skip() ignores the first X items and returns the rest, Take() returns a sequence of the first X items and ignores the rest.  Since they are somewhat of an inverse of each other, it makes sense that their calling signatures are identical (beyond the method name obviously): Take(int count) Returns a sequence containing up to the specified number of items. Anything after the count is ignored. TakeWhile(Func<T, bool> predicate) Returns a sequence containing items as long as the predicate returns true.  Anything from the point the predicate returns false and beyond is ignored. TakeWhile(Func<T, int, bool> predicate) Same as above, but passes not only the item itself to the predicate, but also the index of the item. So, for example, we could do the following: 1: var list = new[] { 1.0, 1.1, 1.2, 2.2, 2.3, 2.4 }; 2:  3: // sequence contains 1.0 and 1.1 4: var firstTwo = list.Take(2); 5:  6: // sequence contains 1.0, 1.1, 1.2 7: var underTwo = list.TakeWhile(i => i < 2.0); The same considerations for SkipWhile() with index apply to TakeWhile() with index, of course.  Using Skip() and Take() for sub-sequences A few weeks back, I talked about The List<T> Range Methods and showed how they could be used to get a sub-list of a List<T>.  This works well if you’re dealing with List<T>, or don’t mind converting to List<T>.  But if you have a simple IEnumerable<T> sequence and want to get a sub-sequence, you can also use Skip() and Take() to much the same effect: 1: var list = new List<double> { 1.0, 1.1, 1.2, 2.2, 2.3, 2.4 }; 2:  3: // results in List<T> containing { 1.2, 2.2, 2.3 } 4: var subList = list.GetRange(2, 3); 5:  6: // results in sequence containing { 1.2, 2.2, 2.3 } 7: var subSequence = list.Skip(2).Take(3); I say “much the same effect” because there are some differences.  First of all GetRange() will throw if the starting index or the count are greater than the number of items in the list, but Skip() and Take() do not.  Also GetRange() is a method off of List<T>, thus it can use direct indexing to get to the items much more efficiently, whereas Skip() and Take() operate on sequences and may actually have to walk through the items they skip to create the resulting sequence.  So each has their pros and cons.  My general rule of thumb is if I’m already working with a List<T> I’ll use GetRange(), but for any plain IEnumerable<T> sequence I’ll tend to prefer Skip() and Take() instead. Summary The Skip() and Take() families of LINQ extension methods are handy for producing sub-sequences from any IEnumerable<T> sequence.  Skip() will ignore the specified number of items and return the rest of the sequence, whereas Take() will return the specified number of items and ignore the rest of the sequence.  Similarly, the SkipWhile() and TakeWhile() methods can be used to skip or take items, respectively, until a given predicate returns false.    Technorati Tags: C#, CSharp, .NET, LINQ, IEnumerable<T>, Skip, Take, SkipWhile, TakeWhile

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  • Combined Likelihood Models

    - by Lukas Vermeer
    In a series of posts on this blog we have already described a flexible approach to recording events, a technique to create analytical models for reporting, a method that uses the same principles to generate extremely powerful facet based predictions and a waterfall strategy that can be used to blend multiple (possibly facet based) models for increased accuracy. This latest, and also last, addition to this sequence of increasing modeling complexity will illustrate an advanced approach to amalgamate models, taking us to a whole new level of predictive modeling and analytical insights; combination models predicting likelihoods using multiple child models. The method described here is far from trivial. We therefore would not recommend you apply these techniques in an initial implementation of Oracle Real-Time Decisions. In most cases, basic RTD models or the approaches described before will provide more than enough predictive accuracy and analytical insight. The following is intended as an example of how more advanced models could be constructed if implementation results warrant the increased implementation and design effort. Keep implemented statistics simple! Combining likelihoods Because facet based predictions are based on metadata attributes of the choices selected, it is possible to generate such predictions for more than one attribute of a choice. We can predict the likelihood of acceptance for a particular product based on the product category (e.g. ‘toys’), as well as based on the color of the product (e.g. ‘pink’). Of course, these two predictions may be completely different (the customer may well prefer toys, but dislike pink products) and we will have to somehow combine these two separate predictions to determine an overall likelihood of acceptance for the choice. Perhaps the simplest way to combine multiple predicted likelihoods into one is to calculate the average (or perhaps maximum or minimum) likelihood. However, this would completely forgo the fact that some facets may have a far more pronounced effect on the overall likelihood than others (e.g. customers may consider the product category more important than its color). We could opt for calculating some sort of weighted average, but this would require us to specify up front the relative importance of the different facets involved. This approach would also be unresponsive to changing consumer behavior in these preferences (e.g. product price bracket may become more important to consumers as a result of economic shifts). Preferably, we would want Oracle Real-Time Decisions to learn, act upon and tell us about, the correlations between the different facet models and the overall likelihood of acceptance. This additional level of predictive modeling, where a single supermodel (no pun intended) combines the output of several (facet based) models into a single prediction, is what we call a combined likelihood model. Facet Based Scores As an example, we have implemented three different facet based models (as described earlier) in a simple RTD inline service. These models will allow us to generate predictions for likelihood of acceptance for each product based on three different metadata fields: Category, Price Bracket and Product Color. We will use an Analytical Scores entity to store these different scores so we can easily pass them between different functions. A simple function, creatively named Compute Analytical Scores, will compute for each choice the different facet scores and return an Analytical Scores entity that is stored on the choice itself. For each score, a choice attribute referring to this entity is also added to be returned to the client to facilitate testing. One Offer To Predict Them All In order to combine the different facet based predictions into one single likelihood for each product, we will need a supermodel which can predict the likelihood of acceptance, based on the outcomes of the facet models. This model will not need to consider any of the attributes of the session, because they are already represented in the outcomes of the underlying facet models. For the same reason, the supermodel will not need to learn separately for each product, because the specific combination of facets for this product are also already represented in the output of the underlying models. In other words, instead of learning how session attributes influence acceptance of a particular product, we will learn how the outcomes of facet based models for a particular product influence acceptance at a higher level. We will therefore be using a single All Offers choice to represent all offers in our combined likelihood predictions. This choice has no attribute values configured, no scores and not a single eligibility rule; nor is it ever intended to be returned to a client. The All Offers choice is to be used exclusively by the Combined Likelihood Acceptance model to predict the likelihood of acceptance for all choices; based solely on the output of the facet based models defined earlier. The Switcheroo In Oracle Real-Time Decisions, models can only learn based on attributes stored on the session. Therefore, just before generating a combined prediction for a given choice, we will temporarily copy the facet based scores—stored on the choice earlier as an Analytical Scores entity—to the session. The code for the Predict Combined Likelihood Event function is outlined below. // set session attribute to contain facet based scores. // (this is the only input for the combined model) session().setAnalyticalScores(choice.getAnalyticalScores); // predict likelihood of acceptance for All Offers choice. CombinedLikelihoodChoice c = CombinedLikelihood.getChoice("AllOffers"); Double la = CombinedLikelihoodAcceptance.getChoiceEventLikelihoods(c, "Accepted"); // clear session attribute of facet based scores. session().setAnalyticalScores(null); // return likelihood. return la; This sleight of hand will allow the Combined Likelihood Acceptance model to predict the likelihood of acceptance for the All Offers choice using these choice specific scores. After the prediction is made, we will clear the Analytical Scores session attribute to ensure it does not pollute any of the other (facet) models. To guarantee our combined likelihood model will learn based on the facet based scores—and is not distracted by the other session attributes—we will configure the model to exclude any other inputs, save for the instance of the Analytical Scores session attribute, on the model attributes tab. Recording Events In order for the combined likelihood model to learn correctly, we must ensure that the Analytical Scores session attribute is set correctly at the moment RTD records any events related to a particular choice. We apply essentially the same switching technique as before in a Record Combined Likelihood Event function. // set session attribute to contain facet based scores // (this is the only input for the combined model). session().setAnalyticalScores(choice.getAnalyticalScores); // record input event against All Offers choice. CombinedLikelihood.getChoice("AllOffers").recordEvent(event); // force learn at this moment using the Internal Dock entry point. Application.getPredictor().learn(InternalLearn.modelArray, session(), session(), Application.currentTimeMillis()); // clear session attribute of facet based scores. session().setAnalyticalScores(null); In this example, Internal Learn is a special informant configured as the learn location for the combined likelihood model. The informant itself has no particular configuration and does nothing in itself; it is used only to force the model to learn at the exact instant we have set the Analytical Scores session attribute to the correct values. Reporting Results After running a few thousand (artificially skewed) simulated sessions on our ILS, the Decision Center reporting shows some interesting results. In this case, these results reflect perfectly the bias we ourselves had introduced in our tests. In practice, we would obviously use a wider range of customer attributes and expect to see some more unexpected outcomes. The facetted model for categories has clearly picked up on the that fact our simulated youngsters have little interest in purchasing the one red-hot vehicle our ILS had on offer. Also, it would seem that customer age is an excellent predictor for the acceptance of pink products. Looking at the key drivers for the All Offers choice we can see the relative importance of the different facets to the prediction of overall likelihood. The comparative importance of the category facet for overall prediction might, in part, be explained by the clear preference of younger customers for toys over other product types; as evident from the report on the predictiveness of customer age for offer category acceptance. Conclusion Oracle Real-Time Decisions' flexible decisioning framework allows for the construction of exceptionally elaborate prediction models that facilitate powerful targeting, but nonetheless provide insightful reporting. Although few customers will have a direct need for such a sophisticated solution architecture, it is encouraging to see that this lies within the realm of the possible with RTD; and this with limited configuration and customization required. There are obviously numerous other ways in which the predictive and reporting capabilities of Oracle Real-Time Decisions can be expanded upon to tailor to individual customers needs. We will not be able to elaborate on them all on this blog; and finding the right approach for any given problem is often more difficult than implementing the solution. Nevertheless, we hope that these last few posts have given you enough of an understanding of the power of the RTD framework and its models; so that you can take some of these ideas and improve upon your own strategy. As always, if you have any questions about the above—or any Oracle Real-Time Decisions design challenges you might face—please do not hesitate to contact us; via the comments below, social media or directly at Oracle. We are completely multi-channel and would be more than glad to help. :-)

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