object tag - Page 452 - Developer IT

dotnet Cologne 2011 : Anmeldung ab 14. März

- by WeigeltRo

Am 6.5.2011 findet in Köln die dotnet Cologne 2011 statt, eine von der .NET User Group Köln und der von mir geleiteten Gruppe Bonn-to-Code.Net gemeinsam organisierte Community-Konferenz rund um .NET. Die “dotnet Cologne” hat sich mittlerweile als die große .NET Community- Konferenz in Deutschland etabliert. So war die letztjährige dotnet Cologne 2010 mit 300 Teilnehmern bereits einen Monat im Voraus ausgebucht. Und heise online schrieb: “Inzwischen besitzt die dotnet Cologne ein weites Einzugsgebiet. Die Teilnehmer kommen nicht mehr ausschließlich aus dem Kölner Umfeld, sondern aus allen Teilen Deutschlands [...] Die gute Qualität des Vorjahres in Verbindung mit einem geringen Preis hat sich schnell herumgesprochen, sodass Teilnehmer aus Bayern oder Thüringen keine Ausnahme waren.” Auch in diesem Jahr erwartet die Teilnehmer ein ganzer Tag voll mit Themen rund um .NET. Auf der Website http://www.dotnet-cologne.de sind dazu jetzt die ersten Vorträge, Sprecher sowie Infos zur Anmeldung veröffentlicht. Die Anmeldung ist ab Montag, den 14.3.2011 um 14:00 freigeschaltet. Es empfiehlt sich, schnell zu handeln, denn für die 100 ersten Teilnehmer gilt der “Super-Early Bird” Preis von nur 25,- Euro; diese Plätze waren letztes Jahr in Nullkommanix weg. Die Teilnehmer 101 – 200 zahlen den “Early Bird” Preis von 40,- Euro, ab Platz 201 gilt der “Normalpreis” von 55,- Euro. Aber egal ob “Super-Early”, “Early” oder “Normal”: 25 Vorträge auf 5 Tracks, gehalten von bekannten Namen der .NET Community, dazu den ganzen Tag über Verpflegung und Getränke – das ist zu diesem Preis ein sehr attraktives Angebot. Wir haben damit eine Konferenz organisiert, die wir selbst gerne besuchen würden. Ganz im Sinne “von Entwicklern, für Entwickler”. Was ist neu? Das Feedback vom letzten Jahr war sehr positiv, den Leuten hat’s einfach gut gefallen. Gleichwohl haben wir Feedback-Bögen, Blog-Einträge und Tweets sehr aufmerksam ausgewertet und bei der Organisation berücksichtigt: Der neue Veranstaltungsort, das Komed im Mediapark Köln, ist zentral gelegen und verfügt über günstige Parkmöglichkeiten Die Räumlichkeiten bieten mehr Platz für Teilnehmer, Sponsoren und natürlich auch das Mittagessen Wir haben dieses Jahr einige etwas speziellere Vorträge auf Level 300 und 400 im Programm, um neben fundierten Einführungen in Themengebiete auch “Deep Dives” für Experten anbieten zu können. Längere Pausen zwischen den Vorträgen ermöglichen es den Teilnehmern besser, nach den Vorträgen mit den Sprechern verbleibende Fragen zu klären, sich an den Sponsorenständen Infos zu holen oder einfach Kontakte mit Gleichgesinnten zu knüpfen. Was das Fördern der Kommunikation unter den Teilnehmern angeht, haben wir schon die eine oder andere Idee im Kopf. Aber einiges davon hängt nicht zuletzt von finanziellen Faktoren ab – und damit sind wir schon beim Thema: Es gibt noch Sponsoring-Möglichkeiten! Die dotnet Cologne 2011 ist die Gelegenheit, Produkte vorzustellen, neue Mitarbeiter zu suchen oder generell den Namen einer Firma bei den richtigen Leuten zu platzieren. Nicht ohne Grund unterstützen uns viele Sponsoren dieses Jahr zum wiederholten Mal. Vom Software-Sponsor für die Verlosung bis hin zum Aussteller vor Ort – es gibt vielfältige Möglichkeiten und wir schicken auf Anfrage gerne unsere Sponsoreninfos zu.

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Cuppa Corner talk "A trip to First Normal Form" available - Domains, Functional Dependencies, Repeat

- by tonyrogerson

It's 15 minutes, I talk about Domains, Functional Dependencies, Repeating Groups, Relational Valued Attributes and of course First Normal Form. http://sqlcontent.sqlblogcasts.com/video/cctr20100507dbdesign1nf/cctr20100507dbdesign1nf.html For questions just ask on the http://sqlserverfaq.com chat control or Twitter using #sqlfaq tag. Slides are also availble here: http://sqlcontent.sqlblogcasts.com/video/cctr20100507dbdesign1nf/cc_tr20100507_dbdesign1nf.pptx...(read more)

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Multi-Threaded Application vs. Single Threaded Application

Why would we use a multi threaded application vs. a single threaded application? First we must define multithreading. Multithreading is a feature of an operating system that allows programs to run subcomponents or threads in parallel. Typically most applications only need to use one thread because they do not perform time consuming tasks. The use of multiple threads allows an application to distribute long running tasks so that they can be executed in parallel. This gives the user the perceived appearance that the application is working faster due to the fact that while one thread is waiting on an IO process the remaining tasks can make use of the available CPU. The allows working threads to execute in tandem so that they can be competed sooner. Multithreading Benefits Improved responsiveness — Users usually report improved responsiveness compared to single thread applications. Faster applications — Multiple threads can lead to improved application performance. Prioritization — Threads can be assigned a priority which would allow higher priority tasks to take precedence over lower priority tasks. Single Threading Benefits Programming and debugging —These activities are easier compared to multithreaded applications due to the reduced complexity Less Overhead — Threads add overhead to an application When developing multi-threaded applications, the following must be considered. Deadlocks occur when two threads hold a monitor that the other one requires. In essence each task is blocking the other and both tasks are waiting for the other monitor to be released. This forces an application to hang or deadlock. Resource allocation is used to prevent deadlocks because the system determines if approving the resource request will render the system in an unsafe state. An unsafe state could result in a deadlock. The system only approves requests that will lead to safe states. Thread Synchronization is used when multiple threads use the same instance of an object. The threads accessing the object can then be locked and then synchronized so that each task can interact with the static object on at a time.

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Easy way to update models in your ASP.NET MVC business layer

- by rajbk

Brad Wilson just mentioned there is a static class ModelCopier that has a static method CopyModel(object from, object to) in the MVC Futures library. It uses reflection to match properties with the same name and compatible types. In short, instead of manually copying over properties as shown here: public void Save(EmployeeViewModel employeeViewModel){ var employee = (from emp in dataContext.Employees where emp.EmployeeID == employeeViewModel.EmployeeID select emp).SingleOrDefault(); if (employee != null) { employee.Address = employeeViewModel.Address; employee.Salary = employeeViewModel.Salary; employee.Title = employeeViewModel.Title; } dataContext.SubmitChanges();} you can use the method like so: public void Save(EmployeeViewModel employeeViewModel){ var employee = (from emp in dataContext.Employees where emp.EmployeeID == employeeViewModel.EmployeeID select emp).SingleOrDefault(); if (employee != null) { ModelCopier.CopyModel(employeeViewModel, employee); } dataContext.SubmitChanges();} Beautiful, isn’t it?

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Using a WCF Message Inspector to extend AppFabric Monitoring

- by Shawn Cicoria

I read through Ron Jacobs post on Monitoring WCF Data Services with AppFabric http://blogs.msdn.com/b/endpoint/archive/2010/06/09/tracking-wcf-data-services-with-windows-server-appfabric.aspx What is immediately striking are 2 things – it’s so easy to get monitoring data into a viewer (AppFabric Dashboard) w/ very little work. And the 2nd thing is, why can’t this be a WCF message inspector on the dispatch side. So, I took the base class WCFUserEventProvider that’s located in the WCF/WF samples [1] in the following path, \WF_WCF_Samples\WCF\Basic\Management\AnalyticTraceExtensibility\CS\WCFAnalyticTracingExtensibility\ and then created a few classes that project the injection as a IEndPointBehavior There are just 3 classes to drive injection of the inspector at runtime via config: IDispatchMessageInspector implementation BehaviorExtensionElement implementation IEndpointBehavior implementation The full source code is below with a link to the solution file here: [Solution File] using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.ServiceModel.Dispatcher; using System.ServiceModel.Channels; using System.ServiceModel; using System.ServiceModel.Configuration; using System.ServiceModel.Description; using Microsoft.Samples.WCFAnalyticTracingExtensibility; namespace Fabrikam.Services { public class AppFabricE2EInspector : IDispatchMessageInspector { static WCFUserEventProvider evntProvider = null; static AppFabricE2EInspector() { evntProvider = new WCFUserEventProvider(); } public object AfterReceiveRequest( ref Message request, IClientChannel channel, InstanceContext instanceContext) { OperationContext ctx = OperationContext.Current; var opName = ctx.IncomingMessageHeaders.Action; evntProvider.WriteInformationEvent("start", string.Format("operation: {0} at address {1}", opName, ctx.EndpointDispatcher.EndpointAddress)); return null; } public void BeforeSendReply(ref System.ServiceModel.Channels.Message reply, object correlationState) { OperationContext ctx = OperationContext.Current; var opName = ctx.IncomingMessageHeaders.Action; evntProvider.WriteInformationEvent("end", string.Format("operation: {0} at address {1}", opName, ctx.EndpointDispatcher.EndpointAddress)); } } public class AppFabricE2EBehaviorElement : BehaviorExtensionElement { #region BehaviorExtensionElement /// <summary> /// Gets the type of behavior. /// </summary> /// <value></value> /// <returns>The type that implements the end point behavior<see cref="T:System.Type"/>.</returns> public override Type BehaviorType { get { return typeof(AppFabricE2EEndpointBehavior); } } /// <summary> /// Creates a behavior extension based on the current configuration settings. /// </summary> /// <returns>The behavior extension.</returns> protected override object CreateBehavior() { return new AppFabricE2EEndpointBehavior(); } #endregion BehaviorExtensionElement } public class AppFabricE2EEndpointBehavior : IEndpointBehavior //, IServiceBehavior { #region IEndpointBehavior public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters) {} public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime) { throw new NotImplementedException(); } public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher) { endpointDispatcher.DispatchRuntime.MessageInspectors.Add(new AppFabricE2EInspector()); } public void Validate(ServiceEndpoint endpoint) { ; } #endregion IEndpointBehavior } } [1] http://www.microsoft.com/downloads/details.aspx?FamilyID=35ec8682-d5fd-4bc3-a51a-d8ad115a8792&displaylang=en

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CodePlex Daily Summary for Sunday, December 19, 2010

CodePlex Daily Summary for Sunday, December 19, 2010Popular ReleasesTeam 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.SQL Monitor: SQL Monitor 3.0 alpha 5: 1. fix a problem with not expanding nodes in object explorer, sorryHacker Passwords: HackerPasswords.zip: Source code, executable and documentationWatchersNET.SiteMap: WatchersNET.SiteMap 01.03.03: Whats NewSkin Object: You can now filter by Terms for Example use: <object id="dnnSITEMAPSL" codetype="dotnetnuke/server" codebase="SITEMAPSL"> <param name="TaxMode" value="terms" /> <param name="TaxTerms" value="TermName1,TermName2" /> </object> changes Tax Term Filter should work correct nowSubtitleTools: 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.EnhSim: EnhSim 2.2.3 ALPHA: 2.2.3 ALPHAThis release adds in the changes for 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 - Added in th...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 (formerly NuPack): 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...Orchard 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...Pyxis 2: Beta 2.2: An issue stopping the Checkbox from working properly has been resolved (gradient background has also been added) A TabDialog control has been added NumericUpDown control added A driver for the VS1053 has been added (not yet in use) PyxisAPI.OpenFile now works with all its features PyxisAPI.SaveFile now works with all features Settings window is now available from the Pyxis menu You can now connect using Static IP or DHCP You can now set your system time from the Settings windo...sgMotion Animation Library: sgMotion v1.3 for SunBurn 2.0.9 [Includes Sample]: sgMotion 1.3 release for use with SunBurn 2.0.9 (all editions). Includes example project with assets, and full Windows and Xbox support. (tested on all platforms)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.DotNetNuke® Community Edition: 05.06.01 Beta: This is the initial Beta of DotNetNuke 5.6.1. See the DotNetNuke Roadmap a full list of changes in this release.MSBuild Extension Pack: December 2010: Release Blog Post The MSBuild Extension Pack December 2010 release provides a collection of over 380 MSBuild tasks. A high level summary of what the tasks currently cover includes the following: System Items: Active Directory, Certificates, COM+, Console, Date and Time, Drives, Environment Variables, Event Logs, Files and Folders, FTP, GAC, Network, Performance Counters, Registry, Services, Sound Code: Assemblies, AsyncExec, CAB Files, Code Signing, DynamicExecute, File Detokenisation, GU...TweetSharp: TweetSharp v2.0.0.0 - Preview 5: 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 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 Numerous fixes reported by preview users Preview 3 ChangesNumerous ...Silverlight Contrib: Silverlight Contrib 2010.1.0: 2010.1.0 New FeaturesCompatibility Release for Silverlight 4 and Visual Studio 2010FlickrNet API Library: 3.1.4000: Newest release. Now contains dedicated Windows Phone 7 DLL as well as all previous DLLs. Also contains Windows Help file documentation now as standard.mojoPortal: 2.3.5.8: see release notes on mojoportal.com http://www.mojoportal.com/mojoportal-2358-released.aspx Note that we have separate deployment packages for .NET 3.5 and .NET 4.0 The deployment package downloads on this page are pre-compiled and ready for production deployment, they contain no C# source code. To download the source code see the Source Code Tab I recommend getting the latest source code using TortoiseHG, you can get the source code corresponding to this release here.Microsoft All-In-One Code Framework: Visual Studio 2010 Code Samples 2010-12-13: Code samples for Visual Studio 2010New ProjectsANLP - Another .NET Lexer Parser: This project aims to have a lexer/parser working in Silverlight and help people to write their own grammar and make the lexer/parser available in Silverlight.Better App Tab Shortcuts Firefox Extension: An extension for Firefox 4.0 which improves the shortcuts for selecting tabs.BizTalk Map Converter: Converts BizTalk Maps into ExcelCampo Minado: Campo minado em SilverlightCSharpHASH: Hash project is an college project conserning business software development. Written in C#.DS_HW1: hw1DynamicViewModel: MVVM using POCOs with .NET 4.0: This project aims to provide a way to implement the Model View ViewModel (MVVM) architectural pattern using Plain Old CLR Objects (POCOs) while taking full advantage of .NET 4.0 DynamicObject Class.Evolution Game: Evolution game that uses genetic algorithms to visualize life of different species.Fluent Parser: Fluent Parser is a library allowing to build a syntaxic analyser in C#. The grammar is built using only .NET objects into the form of a Parsing Expression Grammar (PEG).GoogleMusic Player: Choose and play music from newly launched google Music http://www.google.co.in/music create and save playlists Using C#Gracefully update SharePoint 2010 document metadata: Users want to update the metadata for a document in a document library, for which they don’t have access or if they wanted to update some read-only fields. Hacker Passwords: Hacker Passwords generator - free open sourceHTML5 Canvas FlowView: FlowView is a simple to use API for creating/implementing a flowview style element in HTML5/Canvas. The FlowView looks much like something from Apple's cover view.L#: A F# program to provide similar functionalities offered by Prolog for F# oriented applications.MapInfo Tools: Utilities for working with MapInfo files.Notepad X: Notepad X is an alternative open source text editor for Microsoft Windows, with a lot of customization options created to help users managing text documents, featuring tab navigation.OpenFlyClient: An educational open source of a client written in C# for FlyFF. This is for educational and evaluation purposes only. Using this for private servers is not allowed.Orkut API Library: Orkut API Library (more of a wrapper) for .NET makes it easier for .NET developers creating web and/or desktop applications to leverage Orkut OpenSocial API from within the familiar Visual Studio environment. PasteHtml.NET: PasteHtml.NET is a .NET API for using the PasteHtml.com service.Photon: Silverlight MVVM Framework RSATasync: Running analyses in RiskSpectrum PSA Professional software is a time-consuming task. RSATasync is a middleware, which uses .NET4 Parallel Extensions to parallelize analyses sent by the editor to the analyzer in the RiskSpectrum software.The Killie01 Project: all killie01 projects (opensource)United Nations News for Windows Phone 7: Open source project for United Nations News for Windows Phone 7. WCF SIP Stack: WCF SIPWordpress .NET: WPDotnet is a library to ease the Wordpress integration with ASP.NET. Some Server controls are implemented. If you don't want to use them, you can just use the classes.

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Error trapping for a missing data source in a Spring MVC / Spring JDBC web app [migrated]

- by Geeb

I have written a web app that uses Spring MVC libraries and Spring JDBC to connect to an Oracle DB. (I don't use any ORM type libraries as I create stored procedures on Oracle that do my stuff and I'm quite happy with that.) I use a connection pool to Oracle managed by the Tomcat container The app generally works absolutely fine by the way! BUT... I noticed the other day when I tried to set up the app on another Tomcat instance that I had forgotten to configure the connection pool and obviously the app could not get hold of an org.apache.commons.dbcp.BasicDataSource object, so it crashed. I define the pool params in the tomcat "context.conf" In my "web.xml" I have: <servlet> <servlet-name>appServlet</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/Spring/appServlet/servlet-context.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>appServlet</servlet-name>  <url-pattern>/</url-pattern> </servlet-mapping> <resource-ref> <description>Oracle Datasource example</description> <res-ref-name>jdbc/ora1</res-ref-name> <res-type>org.apache.commons.dbcp.BasicDataSource</res-type> <res-auth>Container</res-auth> </resource-ref> And I have a Spring "servlet-context.xml" where JNDI is used to map the data source object provided by the connection pool to a Spring bean with the ID of "dataSource": <jee:jndi-lookup id="dataSource" jndi-name="java:comp/env/jdbc/ora1" resource-ref="true" /> Here's the question: Where do I trap the case where the database cannot be accessed for whatever reason? I don't want the user to see a yard-and-a-half of Java stack trace in their browser, rather a nicer message that tells them there is a database problem etc. It seems that my app tries to configure the "dataSource" bean (in "servlet-context.xml") before any code has tested it can actually provide a dataSource object from the pool?! Maybe I'm not fully understanding exactly what is going on in these stages of the app firing up ... Thanks for any advice!

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Chunking a List - .NET vs Python

- by Abhijeet Patel

Chunking a List As I mentioned last time, I'm knee deep in python these days. I come from a statically typed background so it's definitely a mental adjustment. List comprehensions is BIG in Python and having worked with a few of them I can see why. Let's say we need to chunk a list into sublists of a specified size. Here is how we'd do it in C# static class Extensions { public static IEnumerable<List<T>> Chunk<T>(this List<T> l, int chunkSize) { if (chunkSize <0) { throw new ArgumentException("chunkSize cannot be negative", "chunkSize"); } for (int i = 0; i < l.Count; i += chunkSize) { yield return new List<T>(l.Skip(i).Take(chunkSize)); } } } static void Main(string[] args) { var l = new List<string> { "a", "b", "c", "d", "e", "f","g" }; foreach (var list in l.Chunk(7)) { string str = list.Aggregate((s1, s2) => s1 + "," + s2); Console.WriteLine(str); } } A little wordy but still pretty concise thanks to LINQ.We skip the iteration number plus chunkSize elements and yield out a new List of chunkSize elements on each iteration. The python implementation is a bit more terse. def chunkIterable(iter, chunkSize): '''Chunks an iterable object into a list of the specified chunkSize ''' assert hasattr(iter, "__iter__"), "iter is not an iterable" for i in xrange(0, len(iter), chunkSize): yield iter[i:i + chunkSize] if __name__ == '__main__': l = ['a', 'b', 'c', 'd', 'e', 'f'] generator = chunkIterable(l,2) try: while(1): print generator.next() except StopIteration: pass xrange generates elements in the specified range taking in a seed and returning a generator. which can be used in a for loop(much like using a C# iterator in a foreach loop) Since chunkIterable has a yield statement, it turns this method into a generator as well. iter[i:i + chunkSize] essentially slices the list based on the current iteration index and chunksize and creates a new list that we yield out to the caller one at a time. A generator much like an iterator is a state machine and each subsequent call to it remembers the state at which the last call left off and resumes execution from that point. The caveat to keep in mind is that since variables are not explicitly typed we need to ensure that the object passed in is iterable using hasattr(iter, "__iter__").This way we can perform chunking on any object which is an "iterable", very similar to accepting an IEnumerable in the .NET land

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Objective C style nil in java?

- by Usman Ismail

Objective C has a concept of a nil object which would accept any method call with any parameters without complaining and silently return another nil. I have used something similar in Java using easymock and mockito for testing. Is there something similar for main line code? Is it even a good idea to have something like this? One use-case where I am considering using it is with optional metrics. We have codahale metrics counters on which we call mark() every time an event is generated. This is surrounded by an If/then to check for metrics enabled flag. I could just use a nil object as counter and silently accept the mark call if metrics are not enabled.

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Silverlight Cream for April 20, 2010 -- #842

- by Dave Campbell

In this Issue: Zoltan Arvai, Svetla Stoycheva, Alexey Zakharov, Chris Rouw, David Anson(-2-), Bill Reiss, John Papa and Adam Kinney, Chris Klug, CorrinaB, and Mike Snow. Shoutouts: Pete Brown interviewed David Kelley at MIX10: Pete at MIX10: David Kelley on the Prototype WPF and Silverlight Retail Experience Pete Brown also interviewed Emil Stoychev at MIX10: Pete at MIX10: Emil Stoychev on the CompletIT Silverlight Site SilverlightShow has a MIX10 Review by SilverlightShow Live Reporter Cigdem Patlak SilverlightShow also has an Interview with SilverlightShow Article Author Andrej Tozon From SilverlightCream.com: Implementing Push Notifications in Windows Phone 7 Zoltan Arvai has a post up on SilverlightShow discussing Push Notification on WP7 ... what it is, and how to use it. Completit.com - the challenges behind building a corporate website in Silverlight Svetla Stoycheva shows off the new CompleteIT corporate website which is pretty darn cool... and disucusses some of the challenges and solutions Introducing to Halcyone - Silverlight Application Framework: Silverlight Rest Extensions Alexey Zakharov has a tutorial up on a Silverlight application framework he's working on called Halcyone which is available on CodePlex Using the Tag Property during Silverlight Binding Chris Rouw details his SL3 to SL4 conversion and some issues he had, and how he was able to resolve a binding problem using the tag property. Using ContextMenu to implement SplitButton and MenuButton for Silverlight (or WPF) David Anson has a cool discussion up of using the ContextMenu code he put up previously to build a Split button, and includes all the code as usual. Silverlight/WPF Data Visualization Development Release 4 and Windows Phone 7 Charting sample! David Anson updated his Data Visualization because of the new releases, and this time he's including WP7... charting in WP7... ! Space Rocks game step 10: More fun with rocks In episode 10, Bill Reiss shows how to deal with multiple asteroids and all the interaction. Silverlight Training Course (Silverlight 4) Get your serious Silverlight 4 Mojo on with a new SL4 Training kit on Channel 9 ... buncha folks, spearheaded (it looks like) by John Papa and Adam Kinney... Plug-ins and composite applications in Silverlight – pt 3 Chris Klug is back with part 3 of his series on extensions and plug-in loading. So far he's covered a roll-your-own concept and MEF, now he digs into Prism. Transitions, Animations, and Effects with Blend - Part One How cool to have CorrinaB speak at your User Group meeting! ... She did just that in Portland, and instead of simply dropping a deck and some code in her blog, she's giving the run-down on her presentation... always good stuff, Corrina! Tip of the Day #110 – Using Static Resources in Class Libraries Mike Snow's latest tip is about how to create and use a Resource Dictionary. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight Silverlight 3 Silverlight 4 Windows Phone MIX10

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How to Build a Tagging System For Blogs

In this article I will cover the basics of how to create a tagging system as seen on other blogs. This system will also have the function of adjusting font size depending on the number of articles that have said tag.

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NullReferenceException when accessing variables in a 2D array in Unity

- by Syed

I have made a class including variables in Monodevelop which is: public class GridInfo : MonoBehaviour { public float initPosX; public float initPosY; public bool inUse; public int f; public int g; public int h; public GridInfo parent; public int y,x; } Now I am using its class variable in another class, Map.cs which is: public class Map : MonoBehaviour { public static GridInfo[,] Tile = new GridInfo[17, 23]; void Start() { Tile[0,0].initPosX = initPosX; //Line 49 } } I am not getting any error on runtime, but when I play in unity it is giving me error NullReferenceException: Object reference not set to an instance of an object Map.Start () (at Assets/Scripts/Map.cs:49) I am not inserting this script in any gameobject, as Map.cs will make a GridInfo type array, I have also tried using variables using GetComponent, where is the problem ?

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OpenIndiana (illumos): vmxnet3 interface lost on reboot

- by protomouse

I want my VMware vmxnet3 interface to be brought up with DHCP on boot. I can manually configure the NIC with: # ifconfig vmxnet3s0 plumb # ipadm create-addr -T dhcp vmxnet3s0/v4dhcp But after creating /etc/dhcp.vmxnet3s0 and rebooting, the interface is down and the logs show: Aug 13 09:34:15 neumann vmxnet3s: [ID 654879 kern.notice] vmxnet3s:0: getcapab(0x200000) -> no Aug 13 09:34:15 neumann vmxnet3s: [ID 715698 kern.notice] vmxnet3s:0: stop() Aug 13 09:34:17 neumann vmxnet3s: [ID 654879 kern.notice] vmxnet3s:0: getcapab(0x200000) -> no Aug 13 09:34:17 neumann vmxnet3s: [ID 920500 kern.notice] vmxnet3s:0: start() Aug 13 09:34:17 neumann vmxnet3s: [ID 778983 kern.notice] vmxnet3s:0: getprop(TxRingSize) -> 256 Aug 13 09:34:17 neumann vmxnet3s: [ID 778983 kern.notice] vmxnet3s:0: getprop(RxRingSize) -> 256 Aug 13 09:34:17 neumann vmxnet3s: [ID 778983 kern.notice] vmxnet3s:0: getprop(RxBufPoolLimit) -> 512 Aug 13 09:34:17 neumann nwamd[491]: [ID 605049 daemon.error] 1: nwamd_set_unset_link_properties: dladm_set_linkprop failed: operation not supported Aug 13 09:34:17 neumann vmxnet3s: [ID 654879 kern.notice] vmxnet3s:0: getcapab(0x20000) -> no Aug 13 09:34:17 neumann nwamd[491]: [ID 751932 daemon.error] 1: nwamd_down_interface: ipadm_delete_addr failed on vmxnet3s0: Object not found Aug 13 09:34:17 neumann nwamd[491]: [ID 819019 daemon.error] 1: nwamd_plumb_unplumb_interface: plumb IPv4 failed for vmxnet3s0: Operation not supported on disabled object Aug 13 09:34:17 neumann nwamd[491]: [ID 160156 daemon.error] 1: nwamd_plumb_unplumb_interface: plumb IPv6 failed for vmxnet3s0: Operation not supported on disabled object Aug 13 09:34:17 neumann nwamd[491]: [ID 771489 daemon.error] 1: add_ip_address: ipadm_create_addr failed on vmxnet3s0: Operation not supported on disabled object Aug 13 09:34:17 neumann nwamd[491]: [ID 405346 daemon.error] 9: start_dhcp: ipadm_create_addr failed for vmxnet3s0: Operation not supported on disabled object I then tried disabling network/physical:nwam in favour of network/physical:default. This works, the interface is brought up but physical:default fails and my network services (e.g. NFS) refuse to start. # ifconfig -a lo0: flags=2001000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4,VIRTUAL> mtu 8232 index 1 inet 127.0.0.1 netmask ff000000 vmxnet3s0: flags=1004843<UP,BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 9000 index 2 inet 192.168.178.248 netmask ffffff00 broadcast 192.168.178.255 vmxnet3s0:1: flags=1004842<BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 9000 index 2 inet 192.168.178.248 netmask ffffff00 broadcast 192.168.178.255 vmxnet3s0:2: flags=1004842<BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 9000 index 2 inet 192.168.178.248 netmask ffffff00 broadcast 192.168.178.255 vmxnet3s0:3: flags=1004842<BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 9000 index 2 inet 192.168.178.248 netmask ffffff00 broadcast 192.168.178.255 vmxnet3s0:4: flags=1004842<BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 9000 index 2 inet 192.168.178.248 netmask ffffff00 broadcast 192.168.178.255 vmxnet3s0:5: flags=1004842<BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 9000 index 2 inet 192.168.178.248 netmask ffffff00 broadcast 192.168.178.255 vmxnet3s0:6: flags=1004842<BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 9000 index 2 inet 192.168.178.248 netmask ffffff00 broadcast 192.168.178.255 vmxnet3s0:7: flags=1004842<BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 9000 index 2 inet 192.168.178.248 netmask ffffff00 broadcast 192.168.178.255 vmxnet3s0:8: flags=1004842<BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 9000 index 2 inet 192.168.178.248 netmask ffffff00 broadcast 192.168.178.255 lo0: flags=2002000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv6,VIRTUAL> mtu 8252 index 1 inet6 ::1/128 vmxnet3s0: flags=20002000840<RUNNING,MULTICAST,IPv6> mtu 9000 index 2 inet6 ::/0 # cat /var/svc/log/network-physical\:default.log [ Aug 16 09:46:39 Enabled. ] [ Aug 16 09:46:41 Executing start method ("/lib/svc/method/net-physical"). ] [ Aug 16 09:46:41 Timeout override by svc.startd. Using infinite timeout. ] starting DHCP on primary interface vmxnet3s0 ifconfig: vmxnet3s0: DHCP is already running [ Aug 16 09:46:43 Method "start" exited with status 96. ] NFS server not running: # svcs -xv network/nfs/server svc:/network/nfs/server:default (NFS server) State: offline since August 16, 2012 09:46:40 AM UTC Reason: Service svc:/network/physical:default is not running because a method failed. See: http://illumos.org/msg/SMF-8000-GE Path: svc:/network/nfs/server:default svc:/milestone/network:default svc:/network/physical:default Reason: Service svc:/network/physical:nwam is disabled. See: http://illumos.org/msg/SMF-8000-GE Path: svc:/network/nfs/server:default svc:/milestone/network:default svc:/network/physical:nwam Reason: Service svc:/network/nfs/nlockmgr:default is disabled. See: http://illumos.org/msg/SMF-8000-GE Path: svc:/network/nfs/server:default svc:/network/nfs/nlockmgr:default See: man -M /usr/share/man -s 1M nfsd Impact: This service is not running. I'm new to the world of Solaris, so any help solving would be much appreciated. Thanks!

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ASP.NET Web API and Simple Value Parameters from POSTed data

- by Rick Strahl

In testing out various features of Web API I've found a few oddities in the way that the serialization is handled. These are probably not super common but they may throw you for a loop. Here's what I found. Simple Parameters from Xml or JSON Content Web API makes it very easy to create action methods that accept parameters that are automatically parsed from XML or JSON request bodies. For example, you can send a JavaScript JSON object to the server and Web API happily deserializes it for you. This works just fine:public string ReturnAlbumInfo(Album album) { return album.AlbumName + " (" + album.YearReleased.ToString() + ")"; } However, if you have methods that accept simple parameter types like strings, dates, number etc., those methods don't receive their parameters from XML or JSON body by default and you may end up with failures. Take the following two very simple methods:public string ReturnString(string message) { return message; } public HttpResponseMessage ReturnDateTime(DateTime time) { return Request.CreateResponse<DateTime>(HttpStatusCode.OK, time); } The first one accepts a string and if called with a JSON string from the client like this:var client = new HttpClient(); var result = client.PostAsJsonAsync<string>(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, "Hello World").Result; which results in a trace like this: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 13Expect: 100-continueConnection: Keep-Alive "Hello World" produces… wait for it: null. Sending a date in the same fashion:var client = new HttpClient(); var result = client.PostAsJsonAsync<DateTime>(http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime, new DateTime(2012, 1, 1)).Result; results in this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 30Expect: 100-continueConnection: Keep-Alive "\/Date(1325412000000-1000)\/" (yes still the ugly MS AJAX date, yuk! This will supposedly change by RTM with Json.net used for client serialization) produces an error response: The parameters dictionary contains a null entry for parameter 'time' of non-nullable type 'System.DateTime' for method 'System.Net.Http.HttpResponseMessage ReturnDateTime(System.DateTime)' in 'AspNetWebApi.Controllers.AlbumApiController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Basically any simple parameters are not parsed properly resulting in null being sent to the method. For the string the call doesn't fail, but for the non-nullable date it produces an error because the method can't handle a null value. This behavior is a bit unexpected to say the least, but there's a simple solution to make this work using an explicit [FromBody] attribute:public string ReturnString([FromBody] string message) andpublic HttpResponseMessage ReturnDateTime([FromBody] DateTime time) which explicitly instructs Web API to read the value from the body. UrlEncoded Form Variable Parsing Another similar issue I ran into is with POST Form Variable binding. Web API can retrieve parameters from the QueryString and Route Values but it doesn't explicitly map parameters from POST values either. Taking our same ReturnString function from earlier and posting a message POST variable like this:var formVars = new Dictionary<string,string>(); formVars.Add("message", "Some Value"); var content = new FormUrlEncodedContent(formVars); var client = new HttpClient(); var result = client.PostAsync(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, content).Result; which produces this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/x-www-form-urlencodedHost: rasxpsContent-Length: 18Expect: 100-continue message=Some+Value When calling ReturnString:public string ReturnString(string message) { return message; } unfortunately it does not map the message value to the message parameter. This sort of mapping unfortunately is not available in Web API. Web API does support binding to form variables but only as part of model binding, which binds object properties to the POST variables. Sending the same message as in the previous example you can use the following code to pick up POST variable data:public string ReturnMessageModel(MessageModel model) { return model.Message; } public class MessageModel { public string Message { get; set; }} Note that the model is bound and the message form variable is mapped to the Message property as would other variables to properties if there were more. This works but it's not very dynamic. There's no real easy way to retrieve form variables (or query string values for that matter) in Web API's Request object as far as I can discern. Well only if you consider this easy:public string ReturnString() { var formData = Request.Content.ReadAsAsync<FormDataCollection>().Result; return formData.Get("message"); } Oddly FormDataCollection does not allow for indexers to work so you have to use the .Get() method which is rather odd. If you're running under IIS/Cassini you can always resort to the old and trusty HttpContext access for request data:public string ReturnString() { return HttpContext.Current.Request.Form["message"]; } which works fine and is easier. It's kind of a bummer that HttpRequestMessage doesn't expose some sort of raw Request object that has access to dynamic data - given that it's meant to serve as a generic REST/HTTP API that seems like a crucial missing piece. I don't see any way to read query string values either. To me personally HttpContext works, since I don't see myself using self-hosted code much.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api 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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Including Amazon affiliate link to Amazon homepage

- by zpesk

I want a link on my Web site that sends the user to the Amazon homepage, but includes my affiliate code so that any subsequent purchases get credited to my account. I have been browsing through the Amazon Associates portal and there only seems to be a way to link to a specific product. I found this link on daringfireball.net: http://www.amazon.com/exec/obidos/redirect?tag=daringfirebal-20&path=subst/home/home.html If I replace his affiliate code (daringfirebal-20) with mine, will this work? is this documented anywhere?

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Should I be using a JavaScript SPA designed when security is important

- by ryanzec

I asked something kind of similar on stackoverflow with a particular piece of code however I want to try to ask this in a broader sense. So I have this web application that I have started to write in backbone using a Single Page Architecture (SPA) however I am starting to second guess myself because of security. Now we are not storing and sending credit card information or anything like that through this web application but we are storing sensitive information that people are uploading to us and will have the ability to re-download too. The obviously security concern that I have with JavaScript is that you can't trust anything that comes from JavaScript however in a Backbone SPA application, everything is being sent through JavaScript. There are two security features that I will have to build in JavaScript; permissions and authentication. The authentication piece is just me override the Backbone.Router.prototype.navigate method to check the fragment it is trying to load and if the JavaScript application.session.loggedIn is not set to true (and they are not viewing a none authenticated page), they are redirected to the login page automatically. The user could easily modify application.session.loggedIn to equal true (or modify Backbone.Router.prototype.navigate method) but then they would also have to not so easily dynamically embedded a link into the page (or modify a current one) that has the proper classes, data-* attributes, and href values to then load a page that should only be loaded when they user has logged in (and has the permissions). So I have an acl object that deals with the permissions stuff. All someone would have to do to view pages or parts of pages they should not be able to is to call acl.addPermission(resource, permission) with the proper permissions or modify the acl.hasPermission() to always return true and then navigate away and then back to the page. Now certain things is EMCAScript 5 like Object.seal() or Object.freeze() would help with some of this however we have to support IE 8 which does not support those pieces of functionality. Now the REST API also performs security checks on every request so technically even if they are able to see parts of the interface that they should not be able to, they still should not be able to actually affect any data. The main benefits for me in developing a JavaScript SPA application is that the application is a lot more responsive since it is only transferring the minimum amount of JSON data for the requested action and performing the minimum amount of work too. There are also other things that I think are beneficial like you are going to have to develop an API for the data (which is good if you want expand your application to different platforms/technologies) or their is more of a separation between front-end and back-end however if security is a concern, it is really wise to go down the road of a JavaScript SPA application for the front-end?

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How I understood monads, part 1/2: sleepless and self-loathing in Seattle

- by Bertrand Le Roy

For some time now, I had been noticing some interest for monads, mostly in the form of unintelligible (to me) blog posts and comments saying “oh, yeah, that’s a monad” about random stuff as if it were absolutely obvious and if I didn’t know what they were talking about, I was probably an uneducated idiot, ignorant about the simplest and most fundamental concepts of functional programming. Fair enough, I am pretty much exactly that. Being the kind of guy who can spend eight years in college just to understand a few interesting concepts about the universe, I had to check it out and try to understand monads so that I too can say “oh, yeah, that’s a monad”. Man, was I hit hard in the face with the limitations of my own abstract thinking abilities. All the articles I could find about the subject seemed to be vaguely understandable at first but very quickly overloaded the very few concept slots I have available in my brain. They also seemed to be consistently using arcane notation that I was entirely unfamiliar with. It finally all clicked together one Friday afternoon during the team’s beer symposium when Louis was patient enough to break it down for me in a language I could understand (C#). I don’t know if being intoxicated helped. Feel free to read this with or without a drink in hand. So here it is in a nutshell: a monad allows you to manipulate stuff in interesting ways. Oh, OK, you might say. Yeah. Exactly. Let’s start with a trivial case: public static class Trivial { public static TResult Execute<T, TResult>( this T argument, Func<T, TResult> operation) { return operation(argument); } } This is not a monad. I removed most concepts here to start with something very simple. There is only one concept here: the idea of executing an operation on an object. This is of course trivial and it would actually be simpler to just apply that operation directly on the object. But please bear with me, this is our first baby step. Here’s how you use that thing: "some string" .Execute(s => s + " processed by trivial proto-monad.") .Execute(s => s + " And it's chainable!"); What we’re doing here is analogous to having an assembly chain in a factory: you can feed it raw material (the string here) and a number of machines that each implement a step in the manufacturing process and you can start building stuff. The Trivial class here represents the empty assembly chain, the conveyor belt if you will, but it doesn’t care what kind of raw material gets in, what gets out or what each machine is doing. It is pure process. A real monad will need a couple of additional concepts. Let’s say the conveyor belt needs the material to be processed to be contained in standardized boxes, just so that it can safely and efficiently be transported from machine to machine or so that tracking information can be attached to it. Each machine knows how to treat raw material or partly processed material, but it doesn’t know how to treat the boxes so the conveyor belt will have to extract the material from the box before feeding it into each machine, and it will have to box it back afterwards. This conveyor belt with boxes is essentially what a monad is. It has one method to box stuff, one to extract stuff from its box and one to feed stuff into a machine. So let’s reformulate the previous example but this time with the boxes, which will do nothing for the moment except containing stuff. public class Identity<T> { public Identity(T value) { Value = value; } public T Value { get; private set;} public static Identity<T> Unit(T value) { return new Identity<T>(value); } public static Identity<U> Bind<U>( Identity<T> argument, Func<T, Identity<U>> operation) { return operation(argument.Value); } } Now this is a true to the definition Monad, including the weird naming of the methods. It is the simplest monad, called the identity monad and of course it does nothing useful. Here’s how you use it: Identity<string>.Bind( Identity<string>.Unit("some string"), s => Identity<string>.Unit( s + " was processed by identity monad.")).Value That of course is seriously ugly. Note that the operation is responsible for re-boxing its result. That is a part of strict monads that I don’t quite get and I’ll take the liberty to lift that strange constraint in the next examples. To make this more readable and easier to use, let’s build a few extension methods: public static class IdentityExtensions { public static Identity<T> ToIdentity<T>(this T value) { return new Identity<T>(value); } public static Identity<U> Bind<T, U>( this Identity<T> argument, Func<T, U> operation) { return operation(argument.Value).ToIdentity(); } } With those, we can rewrite our code as follows: "some string".ToIdentity() .Bind(s => s + " was processed by monad extensions.") .Bind(s => s + " And it's chainable...") .Value; This is considerably simpler but still retains the qualities of a monad. But it is still pointless. Let’s look at a more useful example, the state monad, which is basically a monad where the boxes have a label. It’s useful to perform operations on arbitrary objects that have been enriched with an attached state object. public class Stateful<TValue, TState> { public Stateful(TValue value, TState state) { Value = value; State = state; } public TValue Value { get; private set; } public TState State { get; set; } } public static class StateExtensions { public static Stateful<TValue, TState> ToStateful<TValue, TState>( this TValue value, TState state) { return new Stateful<TValue, TState>(value, state); } public static Stateful<TResult, TState> Execute<TValue, TState, TResult>( this Stateful<TValue, TState> argument, Func<TValue, TResult> operation) { return operation(argument.Value) .ToStateful(argument.State); } } You can get a stateful version of any object by calling the ToStateful extension method, passing the state object in. You can then execute ordinary operations on the values while retaining the state: var statefulInt = 3.ToStateful("This is the state"); var processedStatefulInt = statefulInt .Execute(i => ++i) .Execute(i => i * 10) .Execute(i => i + 2); Console.WriteLine("Value: {0}; state: {1}", processedStatefulInt.Value, processedStatefulInt.State); This monad differs from the identity by enriching the boxes. There is another way to give value to the monad, which is to enrich the processing. An example of that is the writer monad, which can be typically used to log the operations that are being performed by the monad. Of course, the richest monads enrich both the boxes and the processing. That’s all for today. I hope with this you won’t have to go through the same process that I did to understand monads and that you haven’t gone into concept overload like I did. Next time, we’ll examine some examples that you already know but we will shine the monadic light, hopefully illuminating them in a whole new way. Realizing that this pattern is actually in many places but mostly unnoticed is what will enable the truly casual “oh, yes, that’s a monad” comments. Here’s the code for this article: http://weblogs.asp.net/blogs/bleroy/Samples/Monads.zip The Wikipedia article on monads: http://en.wikipedia.org/wiki/Monads_in_functional_programming This article was invaluable for me in understanding how to express the canonical monads in C# (interesting Linq stuff in there): http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marvels-of-monads.aspx

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UserAppDataPath in WPF

- by psheriff

In Windows Forms applications you were able to get to your user's roaming profile directory very easily using the Application.UserAppDataPath property. This folder allows you to store information for your program in a custom folder specifically for your program. The format of this directory looks like this: C:\Users\YOUR NAME\AppData\Roaming\COMPANY NAME\APPLICATION NAME\APPLICATION VERSION For example, on my Windows 7 64-bit system, this folder would look like this for a Windows Forms Application: C:\Users\PSheriff\AppData\Roaming\PDSA, Inc.\WindowsFormsApplication1\1.0.0.0 For some reason Microsoft did not expose this property from the Application object of WPF applications. I guess they think that we don't need this property in WPF? Well, sometimes we still do need to get at this folder. You have two choices on how to retrieve this property. Add a reference to the System.Windows.Forms.dll to your WPF application and use this property directly. Or, you can write your own method to build the same path. If you add a reference to the System.Windows.Forms.dll you will need to use System.Windows.Forms.Application.UserAppDataPath to access this property. Create a GetUserAppDataPath Method in WPF If you want to build this path you can do so with just a few method calls in WPF using Reflection. The code below shows this fairly simple method to retrieve the same folder as shown above. C#using System.Reflection; public string GetUserAppDataPath(){ string path = string.Empty; Assembly assm; Type at; object[] r; // Get the .EXE assembly assm = Assembly.GetEntryAssembly(); // Get a 'Type' of the AssemblyCompanyAttribute at = typeof(AssemblyCompanyAttribute); // Get a collection of custom attributes from the .EXE assembly r = assm.GetCustomAttributes(at, false); // Get the Company Attribute AssemblyCompanyAttribute ct = ((AssemblyCompanyAttribute)(r[0])); // Build the User App Data Path path = Environment.GetFolderPath( Environment.SpecialFolder.ApplicationData); path += @"\" + ct.Company; path += @"\" + assm.GetName().Version.ToString(); return path;} Visual BasicPublic Function GetUserAppDataPath() As String Dim path As String = String.Empty Dim assm As Assembly Dim at As Type Dim r As Object() ' Get the .EXE assembly assm = Assembly.GetEntryAssembly() ' Get a 'Type' of the AssemblyCompanyAttribute at = GetType(AssemblyCompanyAttribute) ' Get a collection of custom attributes from the .EXE assembly r = assm.GetCustomAttributes(at, False) ' Get the Company Attribute Dim ct As AssemblyCompanyAttribute = _ DirectCast(r(0), AssemblyCompanyAttribute) ' Build the User App Data Path path = Environment.GetFolderPath( _ Environment.SpecialFolder.ApplicationData) path &= "\" & ct.Company path &= "\" & assm.GetName().Version.ToString() Return pathEnd Function Summary Getting the User Application Data Path folder in WPF is fairly simple with just a few method calls using Reflection. Of course, there is absolutely no reason you cannot just add a reference to the System.Windows.Forms.dll to your WPF application and use that Application object. After all, System.Windows.Forms.dll is a part of the .NET Framework and can be used from WPF with no issues at all. NOTE: Visit http://www.pdsa.com/downloads to get more tips and tricks like this one. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **We frequently offer a FREE gift for readers of my blog. Visit http://www.pdsa.com/Event/Blog for your FREE gift!

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How to implement Undo and Redo feature in as3

- by Swati Singh

I am going to create an application in that i have to implement an Undo and Redo feature. In the application there will be multiple objects located on stage and user can customize the position of the objects. But when user clicks on Undo the object go back to their default position and after clicking on redo object will move on the new position. So my question is how can i apply these feature in my application? Is there any library or any third party classes? Can some one help me? Thanks in advance.

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How I do VCS

- by Wes McClure

After years of dabbling with different version control systems and techniques, I wanted to share some of what I like and dislike in a few blog posts. To start this out, I want to talk about how I use VCS in a team environment. These come in a series of tips or best practices that I try to follow. Note: This list is subject to change in the future. Always use some form of version control for all aspects of software development. Development is an evolution. Looking back at where we were is an invaluable asset in that process. This includes data schemas and documentation. Reverting / reapplying changes is absolutely critical for efficient development. The tools I use: Code: Hg (preferred), SVN Database: TSqlMigrations Documents: Sometimes in code repository, also SharePoint with versioning Always tag a commit (changeset) with comments This is a quick way to describe to someone else (or your future self) what the changeset entails. Be brief but courteous. One or two sentences about the task, not the actual changes. Use precommit hooks or setup the central repository to reject changes without comments. Link changesets to documentation If your project management system integrates with version control, or has a way to externally reference stories, tasks etc then leave a reference in the commit. This helps locate more information about the commit and/or related changesets. It’s best to have a precommit hook or system that requires this information, otherwise it’s easy to forget. Ability to work offline is required, including commits and history Yes this requires a DVCS locally but doesn’t require the central repository to be a DVCS. I prefer to use either Git or Hg but if it isn’t possible to migrate the central repository, it’s still possible for a developer to push / pull changes to that repository from a local Hg or Git repository. Never lock resources (files) in a central repository… Rude! We have merge tools for a reason, merging sucked a long time ago, it doesn’t anymore… stop locking files! This is unproductive, rude and annoying to other team members. Always review everything in your commit. Never ever commit a set of files without reviewing the changes in each. Never add a file without asking yourself, deep down inside, does this belong? If you leave to make changes during a review, start the review over when you come back. Never assume you didn’t touch a file, double check. This is another reason why you want to avoid large, infrequent commits. Requirements for tools Quickly show pending changes for the entire repository. Default action for a resource with pending changes is a diff. Pluggable diff & merge tool Produce a unified diff or a diff of all changes. This is helpful to bulk review changes instead of opening each file. The central repository is not your own personal dump yard. Breaking this rule is a sure fire way to get the F bomb dropped in front of your name, multiple times. If you turn on Visual Studio’s commit on closing studio option, I will personally break your fingers. By the way, the person(s) in charge of this feature should be fired and never be allowed near programming, ever again. Commit (integrate) to the central repository / branch frequently I try to do this before leaving each day, especially without a DVCS. One never knows when they might need to work from remote the following day. Never commit commented out code If it isn’t needed anymore, delete it! If you aren’t sure if it might be useful in the future, delete it! This is why we have history. If you don’t know why it’s commented out, figure it out and then either uncomment it or delete it. Don’t commit build artifacts, user preferences and temporary files. Build artifacts do not belong in VCS, everything in them is present in the code. (ie: bin\*, obj\*, *.dll, *.exe) User preferences are your settings, stop overriding my preferences files! (ie: *.suo and *.user files) Most tools allow you to ignore certain files and Hg/Git allow you to version this as an ignore file. Set this up as a first step when creating a new repository! Be polite when merging unresolved conflicts. Count to 10, cuss, grab a stress ball and realize it’s not a big deal. Actually, it’s an opportunity to let you know that someone else is working in the same area and you might want to communicate with them. Following the other rules, especially committing frequently, will reduce the likelihood of this. Suck it up, we all have to deal with this unintended consequence at times. Just be careful and GET FAMILIAR with your merge tool. It’s really not as scary as you think. I personally prefer KDiff3 as its merging capabilities rock. Don’t blindly merge and then blindly commit your changes, this is rude and unprofessional. Make sure you understand why the conflict occurred and which parts of the code you want to keep. Apply scrutiny when you commit a manual merge: review the diff! Make sure you test the changes (build and run automated tests) Become intimate with your version control system and the tools you use with it. Avoid trial and error as much as is possible, sit down and test the tool out, read some tutorials etc. Create test repositories and walk through common scenarios. Find the most efficient way to do your work. These tools will be used repetitively, so inefficiencies will add up. Sometimes this involves a mix of tools, both GUI and CLI. I like a combination of both Tortoise Hg and hg cli to get the job efficiently. Always tag releases Create a way to find a given release, whether this be in comments or an explicit tag / branch. This should be readily discoverable. Create release branches to patch bugs and then merge the changes back to other development branch(es). If using feature branches, strive for periodic integrations. Feature branches often cause forked code that becomes irreconcilable. Strive to re-integrate somewhat frequently with the branch this code will ultimately be merged into. This will avoid merge conflicts in the future. Feature branches are best when they are mutually exclusive of active development in other branches. Use and abuse local commits , at least one per task in a story. This builds a trail of changes in your local repository that can be pushed to a central repository when the story is complete. Never commit a broken build or failing tests to the central repository. It’s ok for a local commit to break the build and/or tests. In fact, I encourage this if it helps group the changes more logically. This is one of the main reasons I got excited about DVCS, when I wanted more than one changeset for a set of pending changes but some files could be grouped into both changesets (like solution file / project file changes). If you have more than a dozen outstanding changed resources, there should probably be more than one commit involved. Exceptions when maintaining code bases that require shotgun surgery, in this case, it’s a design smell :) Don’t version sensitive information Especially usernames / passwords There is one area I haven’t found a solution I like yet: versioning 3rd party libraries and/or code. I really dislike keeping any assemblies in the repository, but seems to be a common practice for external libraries. Please feel free to share your ideas about this below. -Wes

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How to prevent ‘Select *’ : The elegant way

- by Dave Ballantyne

I’ve been doing a lot of work with the “Microsoft SQL Server 2012 Transact-SQL Language Service” recently, see my post here and article here for more details on its use and some uses. An obvious use is to interrogate sql scripts to enforce our coding standards. In the SQL world a no-brainer is SELECT *, all apologies must now be given to Jorge Segarra and his post “How To Prevent SELECT * The Evil Way” as this is a blatant rip-off IMO, the only true way to check for this particular evilness is to parse the SQL as if we were SQL Server itself. The parser mentioned above is ,pretty much, the best tool for doing this. So without further ado lets have a look at a powershell script that does exactly that : cls #Load the assembly [System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.Management.SqlParser") | Out-Null $ParseOptions = New-Object Microsoft.SqlServer.Management.SqlParser.Parser.ParseOptions $ParseOptions.BatchSeparator = 'GO' #Create the object $Parser = new-object Microsoft.SqlServer.Management.SqlParser.Parser.Scanner($ParseOptions) $SqlArr = Get-Content "C:\scripts\myscript.sql" $Sql = "" foreach($Line in $SqlArr){ $Sql+=$Line $Sql+="`r`n" } $Parser.SetSource($Sql,0) $Token=[Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::TOKEN_SET $IsEndOfBatch = $false $IsMatched = $false $IsExecAutoParamHelp = $false $Batch = "" $BatchStart =0 $Start=0 $End=0 $State=0 $SelectColumns=@(); $InSelect = $false $InWith = $false; while(($Token = $Parser.GetNext([ref]$State ,[ref]$Start, [ref]$End, [ref]$IsMatched, [ref]$IsExecAutoParamHelp ))-ne [Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::EOF) { $Str = $Sql.Substring($Start,($End-$Start)+1) try{ ($TokenPrs =[Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]$Token) | Out-Null #Write-Host $TokenPrs if($TokenPrs -eq [Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::TOKEN_SELECT){ $InSelect =$true $SelectColumns+="" } if($TokenPrs -eq [Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::TOKEN_FROM){ $InSelect =$false #Write-Host $SelectColumns -BackgroundColor Red foreach($Col in $SelectColumns){ if($Col.EndsWith("*")){ Write-Host "select * is not allowed" exit } } $SelectColumns =@() } }catch{ #$Error $TokenPrs = $null } if($InSelect -and $TokenPrs -ne [Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::TOKEN_SELECT){ if($Str -eq ","){ $SelectColumns+="" }else{ $SelectColumns[$SelectColumns.Length-1]+=$Str } } } OK, im not going to pretend that its the prettiest of powershell scripts, but if our parsed script file “C:\Scripts\MyScript.SQL” contains SELECT * then “select * is not allowed” will be written to the host. So, where can this go wrong ? It cant ,or at least shouldn’t , go wrong, but it is lacking in functionality. IMO, Select * should be allowed in CTEs, views and Inline table valued functions at least and as it stands they will be reported upon. Anyway, it is a start and is more reliable that other methods.

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Deleting multiple objects in a AWS S3 bucket with s3curl.pl?

- by user183394

I have been trying to use the AWS "official" command line tool s3curl.pl to test out the recently announced multi-object delete. Here is what I have done: First, I tested out the s3curl.pl with a set of credentials without a hitch: $ s3curl.pl --id=s3 -- http://testbucket-0.s3.amazonaws.com/|xmllint --format - % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 884 0 884 0 0 4399 0 --:--:-- --:--:-- --:--:-- 5703 <?xml version="1.0" encoding="UTF-8"?> <ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/"> <Name>testbucket-0</Name> <Prefix/> <Marker/> <MaxKeys>1000</MaxKeys> <IsTruncated>false</IsTruncated> <Contents> <Key>file_1</Key> <LastModified>2012-03-22T17:08:17.000Z</LastModified> <ETag>"ee0e521a76524034aaa5b331842a8b4e"</ETag> <Size>400000</Size> <Owner> <ID>e6d81ea69572270e58d3814ab674df8c8f1fd5d502669633a4951bdd5185f7f4</ID> <DisplayName>zackp</DisplayName> </Owner> <StorageClass>STANDARD</StorageClass> </Contents> <Contents> <Key>file_2</Key> <LastModified>2012-03-22T17:08:19.000Z</LastModified> <ETag>"6b32cbf8219a59690a9f69ba6ff3f590"</ETag> <Size>600000</Size> <Owner> <ID>e6d81ea69572270e58d3814ab674df8c8f1fd5d502669633a4951bdd5185f7f4</ID> <DisplayName>zackp</DisplayName> </Owner> <StorageClass>STANDARD</StorageClass> </Contents> </ListBucketResult> Then, I following the s3curl.pl's usage instructions: s3curl.pl --help Usage /usr/local/bin/s3curl.pl --id friendly-name (or AWSAccessKeyId) [options] -- [curl-options] [URL] options: --key SecretAccessKey id/key are AWSAcessKeyId and Secret (unsafe) --contentType text/plain set content-type header --acl public-read use a 'canned' ACL (x-amz-acl header) --contentMd5 content_md5 add x-amz-content-md5 header --put <filename> PUT request (from the provided local file) --post [<filename>] POST request (optional local file) --copySrc bucket/key Copy from this source key --createBucket [<region>] create-bucket with optional location constraint --head HEAD request --debug enable debug logging common curl options: -H 'x-amz-acl: public-read' another way of using canned ACLs -v verbose logging Then, I tried the following, and always got back error. I would appreciated it very much if someone could point out where I made a mistake? $ s3curl.pl --id=s3 --post multi_delete.xml -- http://testbucket-0.s3.amazonaws.com/?delete <?xml version="1.0" encoding="UTF-8"?> <Error><Code>SignatureDoesNotMatch</Code><Message>The request signature we calculated does not match the signature you provided. Check your key and signing method.</Message><StringToSignBytes>50 4f 53 54 0a 0a 0a 54 68 75 2c 20 30 35 20 41 70 72 20 32 30 31 32 20 30 30 3a 35 30 3a 30 38 20 2b 30 30 30 30 0a 2f 7a 65 74 74 61 72 2d 74 2f 3f 64 65 6c 65 74 65</StringToSignBytes><RequestId>707FBE0EB4A571A8</RequestId><HostId>mP3ZwlPTcRqARQZd6gU4UvBrxGBNIVa0VVe5p0rqGmq5hM65RprwcG/qcXe+pmDT</HostId><SignatureProvided>edkNGuugiSFe0ku4eGzkh8kYgHw=</SignatureProvided><StringToSign>POST Thu, 05 Apr 2012 00:50:08 +0000 The file multi_delete.xml contains the following: cat multi_delete.xml <?xml version="1.0" encoding="UTF-8"?> <Delete> <Quiet>true</Quiet> <Object> <Key>file_1</Key> <VersionId> </VersionId>> </Object> <Object> <Key>file_2</Key> <VersionId> </VersionId> </Object> </Delete> Thanks for any help! --Zack

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Operator of the week - Assert

- by Fabiano Amorim

Well my friends, I was wondering how to help you in a practical way to understand execution plans. So I think I'll talk about the Showplan Operators. Showplan Operators are used by the Query Optimizer (QO) to build the query plan in order to perform a specified operation. A query plan will consist of many physical operators. The Query Optimizer uses a simple language that represents each physical operation by an operator, and each operator is represented in the graphical execution plan by an icon. I'll try to talk about one operator every week, but so as to avoid having to continue to write about these operators for years, I'll mention only of those that are more common: The first being the Assert. The Assert is used to verify a certain condition, it validates a Constraint on every row to ensure that the condition was met. If, for example, our DDL includes a check constraint which specifies only two valid values for a column, the Assert will, for every row, validate the value passed to the column to ensure that input is consistent with the check constraint. Assert and Check Constraints: Let's see where the SQL Server uses that information in practice. Take the following T-SQL: IF OBJECT_ID('Tab1') IS NOT NULL DROP TABLE Tab1 GO CREATE TABLE Tab1(ID Integer, Gender CHAR(1)) GO ALTER TABLE TAB1 ADD CONSTRAINT ck_Gender_M_F CHECK(Gender IN('M','F')) GO INSERT INTO Tab1(ID, Gender) VALUES(1,'X') GO To the command above the SQL Server has generated the following execution plan: As we can see, the execution plan uses the Assert operator to check that the inserted value doesn't violate the Check Constraint. In this specific case, the Assert applies the rule, 'if the value is different to "F" and different to "M" than return 0 otherwise returns NULL'. The Assert operator is programmed to show an error if the returned value is not NULL; in other words, the returned value is not a "M" or "F". Assert checking Foreign Keys Now let's take a look at an example where the Assert is used to validate a foreign key constraint. Suppose we have this query: ALTER TABLE Tab1 ADD ID_Genders INT GO IF OBJECT_ID('Tab2') IS NOT NULL DROP TABLE Tab2 GO CREATE TABLE Tab2(ID Integer PRIMARY KEY, Gender CHAR(1)) GO INSERT INTO Tab2(ID, Gender) VALUES(1, 'F') INSERT INTO Tab2(ID, Gender) VALUES(2, 'M') INSERT INTO Tab2(ID, Gender) VALUES(3, 'N') GO ALTER TABLE Tab1 ADD CONSTRAINT fk_Tab2 FOREIGN KEY (ID_Genders) REFERENCES Tab2(ID) GO INSERT INTO Tab1(ID, ID_Genders, Gender) VALUES(1, 4, 'X') Let's look at the text execution plan to see what these Assert operators were doing. To see the text execution plan just execute SET SHOWPLAN_TEXT ON before run the insert command. |--Assert(WHERE:(CASE WHEN NOT [Pass1008] AND [Expr1007] IS NULL THEN (0) ELSE NULL END)) |--Nested Loops(Left Semi Join, PASSTHRU:([Tab1].[ID_Genders] IS NULL), OUTER REFERENCES:([Tab1].[ID_Genders]), DEFINE:([Expr1007] = [PROBE VALUE])) |--Assert(WHERE:(CASE WHEN [Tab1].[Gender]<>'F' AND [Tab1].[Gender]<>'M' THEN (0) ELSE NULL END)) | |--Clustered Index Insert(OBJECT:([Tab1].[PK]), SET:([Tab1].[ID] = RaiseIfNullInsert([@1]),[Tab1].[ID_Genders] = [@2],[Tab1].[Gender] = [Expr1003]), DEFINE:([Expr1003]=CONVERT_IMPLICIT(char(1),[@3],0))) |--Clustered Index Seek(OBJECT:([Tab2].[PK]), SEEK:([Tab2].[ID]=[Tab1].[ID_Genders]) ORDERED FORWARD) Here we can see the Assert operator twice, first (looking down to up in the text plan and the right to left in the graphical plan) validating the Check Constraint. The same concept showed above is used, if the exit value is "0" than keep running the query, but if NULL is returned shows an exception. The second Assert is validating the result of the Tab1 and Tab2 join. It is interesting to see the "[Expr1007] IS NULL". To understand that you need to know what this Expr1007 is, look at the Probe Value (green text) in the text plan and you will see that it is the result of the join. If the value passed to the INSERT at the column ID_Gender exists in the table Tab2, then that probe will return the join value; otherwise it will return NULL. So the Assert is checking the value of the search at the Tab2; if the value that is passed to the INSERT is not found then Assert will show one exception. If the value passed to the column ID_Genders is NULL than the SQL can't show a exception, in that case it returns "0" and keeps running the query. If you run the INSERT above, the SQL will show an exception because of the "X" value, but if you change the "X" to "F" and run again, it will show an exception because of the value "4". If you change the value "4" to NULL, 1, 2 or 3 the insert will be executed without any error. Assert checking a SubQuery: The Assert operator is also used to check one subquery. As we know, one scalar subquery can't validly return more than one value: Sometimes, however, a mistake happens, and a subquery attempts to return more than one value . Here the Assert comes into play by validating the condition that a scalar subquery returns just one value. Take the following query: INSERT INTO Tab1(ID_TipoSexo, Sexo) VALUES((SELECT ID_TipoSexo FROM Tab1), 'F') INSERT INTO Tab1(ID_TipoSexo, Sexo) VALUES((SELECT ID_TipoSexo FROM Tab1), 'F') |--Assert(WHERE:(CASE WHEN NOT [Pass1016] AND [Expr1015] IS NULL THEN (0) ELSE NULL END)) |--Nested Loops(Left Semi Join, PASSTHRU:([tempdb].[dbo].[Tab1].[ID_TipoSexo] IS NULL), OUTER REFERENCES:([tempdb].[dbo].[Tab1].[ID_TipoSexo]), DEFINE:([Expr1015] = [PROBE VALUE])) |--Assert(WHERE:([Expr1017])) | |--Compute Scalar(DEFINE:([Expr1017]=CASE WHEN [tempdb].[dbo].[Tab1].[Sexo]<>'F' AND [tempdb].[dbo].[Tab1].[Sexo]<>'M' THEN (0) ELSE NULL END)) | |--Clustered Index Insert(OBJECT:([tempdb].[dbo].[Tab1].[PK__Tab1__3214EC277097A3C8]), SET:([tempdb].[dbo].[Tab1].[ID_TipoSexo] = [Expr1008],[tempdb].[dbo].[Tab1].[Sexo] = [Expr1009],[tempdb].[dbo].[Tab1].[ID] = [Expr1003])) | |--Top(TOP EXPRESSION:((1))) | |--Compute Scalar(DEFINE:([Expr1008]=[Expr1014], [Expr1009]='F')) | |--Nested Loops(Left Outer Join) | |--Compute Scalar(DEFINE:([Expr1003]=getidentity((1856985942),(2),NULL))) | | |--Constant Scan | |--Assert(WHERE:(CASE WHEN [Expr1013]>(1) THEN (0) ELSE NULL END)) | |--Stream Aggregate(DEFINE:([Expr1013]=Count(*), [Expr1014]=ANY([tempdb].[dbo].[Tab1].[ID_TipoSexo]))) | |--Clustered Index Scan(OBJECT:([tempdb].[dbo].[Tab1].[PK__Tab1__3214EC277097A3C8])) |--Clustered Index Seek(OBJECT:([tempdb].[dbo].[Tab2].[PK__Tab2__3214EC27755C58E5]), SEEK:([tempdb].[dbo].[Tab2].[ID]=[tempdb].[dbo].[Tab1].[ID_TipoSexo]) ORDERED FORWARD) You can see from this text showplan that SQL Server as generated a Stream Aggregate to count how many rows the SubQuery will return, This value is then passed to the Assert which then does its job by checking its validity. Is very interesting to see that the Query Optimizer is smart enough be able to avoid using assert operators when they are not necessary. For instance: INSERT INTO Tab1(ID_TipoSexo, Sexo) VALUES((SELECT ID_TipoSexo FROM Tab1 WHERE ID = 1), 'F') INSERT INTO Tab1(ID_TipoSexo, Sexo) VALUES((SELECT TOP 1 ID_TipoSexo FROM Tab1), 'F') For both these INSERTs, the Query Optimiser is smart enough to know that only one row will ever be returned, so there is no need to use the Assert. Well, that's all folks, I see you next week with more "Operators". Cheers, Fabiano

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Why do you need float/double?

- by acidzombie24

I was watching http://www.joelonsoftware.com/items/2011/06/27.html and laughed at Jon Skeet joke about 0.3 not being 0.3. I personally never had problems with floats/decimals/doubles but then I remember I learned 6502 very early and never needed floats in most of my programs. The only time I used it was for graphics and math where inaccurate numbers were ok and the output was for the screen and not to be stored (in a db, file) or dependent on. My question is, where are places were you typically use floats/decimals/double? So I know to watch out for these gotchas. With money I use longs and store values by the cent, for speed of an object in a game I add ints and divide (or bitshift) the value to know if I need to move a pixel or not. (I made object move in the 6502 days, we had no divide nor floats but had shifts). So I was mostly curious.

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International Radio Operators Alphabet in F# & Silverlight – Part 2

- by MarkPearl

So the brunt of my my very complex F# code has been done. Now it’s just putting the Silverlight stuff in. The first thing I did was add a new project to my solution. I gave it a name and VS2010 did the rest of the magic in creating the .Web project etc. In this instance because I want to take the MVVM approach and make use of commanding I have decided to make the frontend a Silverlight4 project. I now need move my F# code into a proper Silverlight Library. Warning – when you create the Silverlight Library VS2010 will ask you whether you want it to be based on Silverlight3 or Silverlight4. I originally went for Silverlight4 only to discover when I tried to compile my solution that I was given an error… Error 12 F# runtime for Silverlight version v4.0 is not installed. Please go to http://go.microsoft.com/fwlink/?LinkId=177463 to download and install matching.. After asking around I discovered that the Silverlight4 F# runtime is not available yet. No problem, the suggestion was to change the F# Silverlight Library to a Silverlight3 project however when going to the properties of the project file – even though I changed it to Silverlight3, VS2010 did not like it and kept reverting it to a Silverlight4 project. After a few minutes of scratching my head I simply deleted Silverlight4 F# Library project and created a new F# Silverlight Library project in Silverlight3 and VS2010 was happy. Now that the project structure is set up, rest is fairly simple. You need to add the Silverlight Library as a reference to the C# Silverlight Front End. Then setup your views, since I was following the MVVM pattern I made a Views & ViewModel folder and set up the relevant View and ViewModels. The MainPageViewModel file looks as follows using System; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Ink; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using System.Collections.ObjectModel; namespace IROAFrontEnd.ViewModels { public class MainPageViewModel : ViewModelBase { private string _iroaString; private string _inputCharacters; public string InputCharacters { get { return _inputCharacters; } set { if (_inputCharacters != value) { _inputCharacters = value; OnPropertyChanged("InputCharacters"); } } } public string IROAString { get { return _iroaString; } set { if (_iroaString != value) { _iroaString = value; OnPropertyChanged("IROAString"); } } } public ICommand MySpecialCommand { get { return new MyCommand(this); } } public class MyCommand : ICommand { readonly MainPageViewModel _myViewModel; public MyCommand(MainPageViewModel myViewModel) { _myViewModel = myViewModel; } public event EventHandler CanExecuteChanged; public bool CanExecute(object parameter) { return true; } public void Execute(object parameter) { var result = ModuleMain.ConvertCharsToStrings(_myViewModel.InputCharacters); var newString = ""; foreach (var Item in result) { newString += Item + " "; } _myViewModel.IROAString = newString.Trim(); } } } } One of the features I like in Silverlight4 is the new commanding. You will notice in my I have put the code under the command execute to reference to my F# module. At the moment this could be cleaned up even more, but will suffice for now.. public void Execute(object parameter) { var result = ModuleMain.ConvertCharsToStrings(_myViewModel.InputCharacters); var newString = ""; foreach (var Item in result) { newString += Item + " "; } _myViewModel.IROAString = newString.Trim(); } I then needed to set the view up. If we have a look at the MainPageView.xaml the xaml code will look like the following…. Nothing to fancy, but battleship grey for now… take careful note of the binding of the command in the button to MySpecialCommand which was created in the ViewModel. <UserControl x:Class="IROAFrontEnd.Views.MainPageView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400"> <Grid x:Name="LayoutRoot" Background="White"> <Grid.RowDefinitions> <RowDefinition/> <RowDefinition/> <RowDefinition/> </Grid.RowDefinitions> <TextBox Grid.Row="0" Text="{Binding InputCharacters, Mode=TwoWay}"/> <Button Grid.Row="1" Command="{Binding MySpecialCommand}"> <TextBlock Text="Generate"/> </Button> <TextBlock Grid.Row="2" Text="{Binding IROAString}"/> </Grid> </UserControl> Finally in the App.xaml.cs file we need to set the View and link it to the ViewModel. private void Application_Startup(object sender, StartupEventArgs e) { var myView = new MainPageView(); var myViewModel = new MainPageViewModel(); myView.DataContext = myViewModel; this.RootVisual = myView; } Once this is done – hey presto – it worked. I typed in some “Test Input” and clicked the generate button and the correct Radio Operators Alphabet was generated. And that’s the end of my first very basic F# Silverlight application.

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