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• Detecting Connection Speed / Bandwidth in .net/WCF

  - by Mystagogue

  I'm writing both client and server code using WCF, where I need to know the "perceived" bandwidth of traffic between the client and server. I could use ping statistics to gather this information separately, but I wonder if there is a way to configure the channel stack in WCF so that the same statistics can be gathered simultaneously while performing my web service invocations. This would be particularly useful in cases where ICMP is disabled (e.g. ping won't work). In short, while making my regular business-related web service calls (REST calls to be precise), is there a way to collect connection speed data implicitly? Certainly I could time the web service round trip, compared to the size of data used in the round-trip, to give me an idea of throughput - but I won't know how much of that perceived bandwidth was network related, or simply due to server-processing latency. I could perhaps solve that by having the server send back a time delta, representing server latency, so that the client can compute the actual network traffic time. If a more sophisticated approach is not available, that might be my answer...

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• What is the performance penalty of XML data type in SQL Server when compared to NVARCHAR(MAX)?

  - by Piotr Owsiak

  I have a DB that is going to keep log entries. One of the columns in the log table contains serialized (to XML) objects and a guy on my team proposed to go with XML data type rather than NVARCHAR(MAX). This table will have logs kept "forever" (archiving some very old entries may be considered in the future). I'm a little worried about the CPU overhead, but I'm even more worried that DB can grow faster (FoxyBOA from the referenced question got 70% bigger DB when using XML). I have read this question http://stackoverflow.com/questions/514827/microsoft-sql-server-2005-2008-xml-vs-text-varchar-data-type and it gave me some ideas but I am particulairly interrested in clarification on whether the DB size increases or decreases. Can you please share your insight/experiences in that matter. BTW. I don't currently have any need to depend on XML features within SQL Server (there's nearly zero advantage to me in the specific case). Ocasionally log entries will be extracted, but I prefer to handle the XML using .NET (either by writing a small client or using a function defined in a .NET assembly).

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• Declare module name of classes for logging

  - by Space_C0wb0y

  I currently am adding some features to our logging-library. One of these is the possibility to declare a module-name for a class that automatically gets preprended to any log-messages writing from within that class. However, if no module-name is provided, nothing is prepended. Currently I am using a trait-class that has a static function that returns the name. template< class T > struct ModuleNameTrait { static std::string Value() { return ""; } }; template< > struct ModuleNameTrait< Foo > { static std::string Value() { return "Foo"; } }; This class can be defined using a helper-macro. The drawback is, that the module-name has to be declared outside of the class. I would like this to be possible within the class. Also, I want to be able to remove all logging-code using a preprocessor directive. I know that using SFINAE one can check if a template argument has a certain member, but since other people, that are not as friendly with templates as I am, will have to maintain the code, I am looking for a much simpler solution. If there is none, I will stick with the traits approach. Thanks in advance!

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• iPhone and OpenCV

  - by gn-mithun

  Hello, I am writing an application to create a movie file from a bunch of images on an iPhone. I am using OpenCv. I downloaded openCv static libraries for arm(iPhones native instruction architecture) and the libraries were generated just fine. There were no problems linking to them libraries. As a first step, i was trying to create a .avi file using one image, to see if it works. But cvCreateVideoWriter always returns me a NULL value. I did some searchin and i believe its due to the codec not being present. I am trying this on the iPhone simulator. this is what i do... (void)viewDidLoad { [super viewDidLoad]; UIImage *anImage = [UIImage imageNamed:@"1.jpg"]; IplImage *img_color = [self CreateIplImageFromUIImage:anImage]; //The image gets created just fine CvVideoWriter *writer = cvCreateVideoWriter("out.avi",CV_FOURCC('P','I','M','1'), 25,cvSize(320,480),1); //writer is always null int result = cvWriteFrame(writer, img_color); NSLog(@"\n%d",result); //hence this is also 0 all the time cvReleaseVideoWriter(&writer); } I am not sure about the the second parameter. What sort of codec or what exactly it does... I am a n00B in this. Any suggestions?

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• Return a list of important Python modules in a script?

  - by Jono Bacon

  Hi All, I am writing a program that categorizes a list of Python files by which modules they import. As such I need to scan the collection of .py files ad return a list of which modules they import. As an example, if one of the files I import has the following lines: import os import sys, gtk I would like it to return: ["os", "sys", "gtk"] I played with modulefinder and wrote: from modulefinder import ModuleFinder finder = ModuleFinder() finder.run_script('testscript.py') print 'Loaded modules:' for name, mod in finder.modules.iteritems(): print '%s ' % name, but this returns more than just the modules used in the script. As an example in a script which merely has: import os print os.getenv('USERNAME') The modules returned from the ModuleFinder script return: tokenize heapq __future__ copy_reg sre_compile _collections cStringIO _sre functools random cPickle __builtin__ subprocess cmd gc __main__ operator array select _heapq _threading_local abc _bisect posixpath _random os2emxpath tempfile errno pprint binascii token sre_constants re _abcoll collections ntpath threading opcode _struct _warnings math shlex fcntl genericpath stat string warnings UserDict inspect repr struct sys pwd imp getopt readline copy bdb types strop _functools keyword thread StringIO bisect pickle signal traceback difflib marshal linecache itertools dummy_thread posix doctest unittest time sre_parse os pdb dis ...whereas I just want it to return 'os', as that was the module used in the script. Can anyone help me achieve this?

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• Dataflow Pipeline holding on to memory

  - by Jesse Carter

  I've created a Dataflow pipeline consisting of 4 blocks (which includes one optional block) which is responsible for receiving a query object from my application across HTTP and retrieving information from a database, doing an optional transform on that data, and then writing the information back in the HTTP response. In some testing I've done I've been pulling down a significant amount of data from the database (570 thousand rows) which are stored in a List object and passed between the different blocks and it seems like even after the final block has been completed the memory isn't being released. Ram usage in Task Manager will spike up to over 2 GB and I can observe several large spikes as the List hits each block. The signatures for my blocks look like this: private TransformBlock<HttpListenerContext, Tuple<HttpListenerContext, QueryObject>> m_ParseHttpRequest; private TransformBlock<Tuple<HttpListenerContext, QueryObject>, Tuple<HttpListenerContext, QueryObject, List<string>>> m_RetrieveDatabaseResults; private TransformBlock<Tuple<HttpListenerContext, QueryObject, List<string>>, Tuple<HttpListenerContext, QueryObject, List<string>>> m_ConvertResults; private ActionBlock<Tuple<HttpListenerContext, QueryObject, List<string>>> m_ReturnHttpResponse; They are linked as follows: m_ParseHttpRequest.LinkTo(m_RetrieveDatabaseResults); m_RetrieveDatabaseResults.LinkTo(m_ConvertResults, tuple => tuple.Item2 is QueryObjectA); m_RetrieveDatabaseResults.LinkTo(m_ReturnHttpResponse, tuple => tuple.Item2 is QueryObjectB); m_ConvertResults.LinkTo(m_ReturnHttpResponse); Is it possible that I can set up the pipeline such that once each block is done with the list they no longer need to hold on to it as well as once the entire pipeline is completed that the memory is released?

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• Problem with UserControl with custom Dependency Property

  - by Mathias Koch

  Hi, I'm writing a user control with a dependency property for a search text called SearchText. It is a dependency property because I want to allow consumers of the control to use data binding. The user control contains a WPF TextBox where the user can enter the search text. I could use data binding to connect the SearchText dependency property of the user control with the Text dependency property of the TextBox, but this binding only fires when the text box looses input focus. What I want is SearchText to be updated after every change of Text. So I have added a TextChanged event handler to the user control where I set SearchText to the value of Text. My Problem is, the SearchText binding doesn't work, the source never gets updated. What am I doing wrong? Here's the relevant part of the user controls code-behind: public partial class UserControlSearchTextBox : UserControl { public string SearchText { get { return (string)GetValue(SearchTextProperty); } set { SetValue(SearchTextProperty, value); } } public static readonly DependencyProperty SearchTextProperty = DependencyProperty.Register("SearchText", typeof(string), typeof(UserControlSearchTextBox), new UIPropertyMetadata("")); private void TextBox_TextChanged(object sender, TextChangedEventArgs e) { SearchText = ((TextBox)sender).Text; } ... } The window that contains an instance of the user control has its DataContext set to an object that has a property also called SearchText. <uc:UserControlSearchTextBox SearchText="{Binding SearchText}" /> The data context of the Window: public class DataSourceUserManual : DataSourceBase { private string _searchText; public string SearchText { get { return _searchText; } set { _searchText = value; ... OnPropertyChanged("SearchText"); } } } Unfortunately, this setter is not called when I type into the text box. Any ideas?

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• Hierarchical object model with property inheritance and event bubbling?

  - by Winston Fassett

  I'm writing a document-based client application and I need a DOM or WPF-like, but non-visual model that: Is a tree composed of elements Can accept an unlimited number of custom properties that get/set any CLR type, including collections. Can inherit their values from their parent Can inherit their default values from an ancestor Can be derived/calculated from other properties, ancestors, or descendants Support event bubbling / tunneling There will be a core set of properties but other plugins may add their own or even create custom documents Supports full inspection by the owning document in order to persist the tree and attributes in an XML format. I realize that's a tall order but I was really hoping there would be something out there to help me get started. Unfortunately WPF DependencyObjects are too closed, proprietary, and coupled to WPF to be of any use as a document model. My needs also have a strong resemblance to the HTML DOM but I haven't been able to find any clean DOM implementations that could be decoupled from HTML or ported to .NET. My current platform is .NET/C# but if anyone knows of anything that might be useful for inspiration or embedding, regardless of the platform, I'd love to know.

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• Equivalent Carbon 32-bit call for using in 64-bit application - GetApplicationEventTarget().

  - by Dheeraj

  Hi All, I'm writing a 64-bit Cocoa application. I need to register for global key events. So I wrote this piece of code : - (void)awakeFromNib { EventHotKeyRef gMyHotKeyRef; EventHotKeyID gMyHotKeyID; EventTypeSpec eventType; eventType.eventClass=kEventClassKeyboard; eventType.eventKind=kEventHotKeyPressed; eventType.eventClass=kEventClassKeyboard; eventType.eventKind=kEventHotKeyPressed; InstallApplicationEventHandler(&MyHotKeyHandler,1,&eventType,NULL,NULL); gMyHotKeyID.signature='htk1'; gMyHotKeyID.id=1; RegisterEventHotKey(49, cmdKey+optionKey, gMyHotKeyID, **GetApplicationEventTarget**(), 0, &gMyHotKeyRef); } But since GetApplicationEventTarget() is not supported for 64-bit applications I'm getting errors. If I declare it, then I don't get any errors but the application crashes. Is there any equivalent method for GetApplicationEventTarget() (defined in Carbon framework) to use in 64-bit applications. Or is there any way to get the global key events using cocoa calls? Any help is appreciated. Thanks, Dheeraj.

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• backbone.js Model.get() returns undefined, scope using coffeescript + coffee toaster?

  - by benipsen

  I'm writing an app using coffeescript with coffee toaster (an awesome NPM module for stitching) that builds my app.js file. Lots of my application classes and templates require info about the current user so I have an instance of class User (extends Backbone.Model) stored as a property of my main Application class (extends Backbone.Router). As part of the initialization routine I grab the user from the server (which takes care of authentication, roles, account switching etc.). Here's that coffeescript: @user = new models.User @user.fetch() console.log(@user) console.log(@user.get('email')) The first logging statement outputs the correct Backbone.Model attributes object in the console just as it should: User _changing: false _escapedAttributes: Object _pending: Object _previousAttributes: Object _silent: Object attributes: Object account: Object created_on: "1983-12-13 00:00:00" email: "[email protected]" icon: "0" id: "1" last_login: "2012-06-07 02:31:38" name: "Ben Ipsen" roles: Object __proto__: Object changed: Object cid: "c0" id: "1" __proto__: ctor app.js:228 However, the second returns undefined despite the model attributes clearly being there in the console when logged. And just to make things even more interesting, typing "window.app.user.get('email')" into the console manually returns the expected value of "[email protected]"... ? Just for reference, here's how the initialize method compiles into my app.js file: Application.prototype.initialize = function() { var isMobile; isMobile = navigator.userAgent.match(/(iPhone|iPod|iPad|Android|BlackBerry)/); this.helpers = new views.DOMHelpers().initialize().setup_viewport(isMobile); this.user = new models.User(); this.user.fetch(); console.log(this.user); console.log(this.user.get('email')); return this; }; I initialize the Application controller in my static HTML like so: jQuery(document).ready(function(){ window.app = new controllers.Application(); }); Suggestions please and thank you!

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• jQuery crashing Internet Explorer

  - by Bradley Bell

  Hello. Okay basically, I'm designing and developing a fairly complicated website which revolves around the use of jQuery.. My knowlege of jQuery is really poor and this is the first time I've properly used it. I posted a question here before about the script and apparently its awful, but I didn't show you exactly what I was actually writing it for, which I can now.. Because I've uploaded it onto a test directory. It now works fine in every browser other than IE. The CSS styling is getting there and it should be close to finish soon! However, Internet Explorer is showing bad problems.. In IE 7,8 it looks fine but when you go to hover over a link, it immediately crashes. IE 6, the display doesn't seem to be working properly at all. But IE 6 is a lesser problem. If you could take just 5 or 10 minutes to potentially rewrite a simple script which would potentially take me 10 hours, I would be so so grateful! Heres the site - http://openyourheart.org.uk/test/index.html I can send all the files zipped if required. Thankyou in advance. Bradley

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• How can "today's date" be varied for unit testing purposes?

  - by ck

  I use VS2008 targetting .NET 2.0 Framework, and, just in case, no I can't change this :) I have a DateCalculator class. Its method GetNextExpirationDate attempts to determine the next expiration, internally using DateTime.Today as a baseline date. As I was writing unit tests, I realized that I wanted to test GetNextExpirationDate for different 'today' dates. What's the best way to do this? Here are some alternatives I've considered: Expose a property/overloaded method with argument baselineDate and only use it from the unit test. In actual client code, disregard the property/overloaded method in favour of the method that defaults baselineDate to DateTime.Today. I'm reluctant to do this as it makes the public interface of the DateCalculator class awkward. Create a protected field called baselineDate that is internally set to DateTime.Today. When testing, derive a DateCalculatorForTesting from DateCalculator and set baslineDate via the constructor. It keeps the public interface clean, but still isn't great - baselineDate was made protected and a derived class is required, both solely for testing. Use extension methods. I tried this after adding the ExtensionAttribute, then realized it wouldn't work because extension methods can't access private/protected variables. I initially thought this was really quite an elegant solution. :( I'd be interested in hearing what others think.

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• Injecting Dependencies into Domain Model classes with Nhibernate (ASP.NET MVC + IOC)

  - by Sunday Ironfoot

  I'm building an ASP.NET MVC application that uses a DDD (Domain Driven Design) approach with database access handled by NHibernate. I have domain model class (Administrator) that I want to inject a dependency into via an IOC Container such as Castle Windsor, something like this: public class Administrator { public virtual int Id { get; set; } //.. snip ..// public virtual string HashedPassword { get; protected set; } public void SetPassword(string plainTextPassword) { IHashingService hasher = IocContainer.Resolve<IHashingService>(); this.HashedPassword = hasher.Hash(plainTextPassword); } } I basically want to inject IHashingService for the SetPassword method without calling the IOC Container directly (because this is suppose to be an IOC Anti-pattern). But I'm not sure how to go about doing it. My Administrator object either gets instantiated via new Administrator(); or it gets loaded via NHibernate, so how would I inject the IHashingService into the Administrator class? On second thoughts, am I going about this the right way? I was hoping to avoid having my codebase littered with... currentAdmin.Password = HashUtils.Hash(password, Algorithm.Sha512); ...and instead get the domain model itself to take care of hashing and neatly encapsulate it away. I can envisage another developer accidently choosing the wrong algorithm and having some passwords as Sha512, and some as MD5, some with one salt, and some with a different salt etc. etc. Instead if developers are writing... currentAdmin.SetPassword(password); ...then that would hide those details away and take care of those problems listed above would it not?

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• Developing cross platform mobile application

  - by sohilv

  More and more mobile platforms are being launched and sdk's are available to developers. There are various mobile platform are available, Android,iOS,Moblin,Windows mobile 7,RIM,symbian,bada,maemo etc. And making of corss platform application is headache for developers. I am searching common thing across the platforms which will help to developers who want to port application to all platforms.Like what is the diff screen resolution, input methods, open gl support etc. please share details that you know for the any of platform . or is there possibilities , by writing code in html (widget type of thing) and load it into native application. I know about the android , in which we can add the web view into application. by calling setContentView(view) Please share the class details where we can add the html view into native application of different type of platforms that you know. Purpose of this thread is share common details across developers. marking as community wiki. Cross platform tools & library XMLVM and iSpectrum (cross compile Java code from an Android app or creating one from scratch Phone Gap (cross platform mobile apps) Titanium (to build native mobile and desktop apps with web technologies) Mono Touch ( C# for iphone ) rhomobile - http://rhomobile.com/ samples are here: http://github.com/rhomobile/rhodes-system-api-samples Sencha Touch - Sencha Touch is a HTML5 mobile app framework that allows you to develop web apps that look and feel native on Apple iOS and Google Android touchscreen devices. http://www.sencha.com/products/touch/ Corona - Iphone/Ipad / Android application cross platform library . Too awesome. http://anscamobile.com/corona/ A guide to port existing Android app to Windows Phone 7 http://windowsphone.interoperabilitybridges.com/articles/windows-phone-7-guide-for-iphone-application-developers

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• Open the Word Application from a button on a web page

  - by Andrea

  I'm developing a proof of concept web application: A web page with a button that opens the Word Application installed on the user's PC. I'm stuck with a C# project in Visual Studio 2008 Express (Windows XP client, LAMP server). I've followed the Writing an ActiveX Control in .NET tutorial and after some tuning it worked fine. Then I added my button for opening Word. The problem is that I can reference the Microsoft.Office.Interop.Word from the project, but I'm not able to access it from the web page. The error says "That assembly does not allow partially trusted callers". I've read a lot about security in .NET, but I'm totally lost now. Disclaimer: I'm into .NET since 4 days ago. I've tried to work around this issue but I cannot see the light!! I don't even know if it will ever be possible! using System; using System.Collections.Generic; using System.ComponentModel; using System.Drawing; using System.Data; using System.Linq; using System.Text; using System.Windows.Forms; using Word = Microsoft.Office.Interop.Word; using System.IO; using System.Security.Permissions; using System.Security; [assembly: AllowPartiallyTrustedCallers] namespace OfficeAutomation { public partial class UserControl1 : UserControl { public UserControl1() { InitializeComponent(); } private void openWord_Click(object sender, EventArgs e) { try { Word.Application Word_App = null; Word_App = new Word.Application(); Word_App.Visible = true; } catch (Exception exc) { MessageBox.Show("Can't open Word application (" + exc.ToString() + ")"); } } } }

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• Culture Sensitive GetHashCode

  - by user114928

  Hi, I'm writing a c# application that will process some text and provide basic query functions. In order to ensure the best possible support for other languages, I am allowing the users of the application to specify the System.Globalization.CultureInfo (via the "en-GB" style code) and also the full range of collation options using the System.Globalization.CompareOptions flags enum. For regular string comparison I'm then using a combination of: a) String.Compare overload that accepts the culture and options b) For some bulk processes I'm caching the byte data (KeyData) from CompareInfo.GetSortKey (overload that accepts the options) and using a byte-by-byte comparison of the KeyData. This seemed fine (although please comment if you think these two methods shouldn't be mixed), but then I had reason to use the HashSet< class which only has an overload for IEqualityComparer<. MS documentation seems to suggest that I should use StringComparer (which implements both IEqualityComparer< and IComparer<), but this only seems to support the "IgnoreCase" option from CompareOptions and not "IgnoreKanaType", "IgnoreSymbols", "IgnoreWidth" etc. I'm assuming that a StringComparer that ignores these other options could produce different hashcodes for two strings that might be considered the same using my other comparison options. I'd therefore get incorrect results from my application. Only thought at the moment is to create my own IEqualityComparer< that generates a hashcode from the SortKey.KeyData and compares eqality be using the String.Compare overload. Any suggestions?

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• Get reference to all instances of jquery ui widget?

  - by Hailwood

  I am writing a jquery UI widget that simply wraps the bootstrap popover plugin, In the widget you can pass in the option 'singular', if this is passed in then it should call a function of all other instances of the plugin. something like $('#one').myWidget(); $('#two').myWidget(); $('#three').myWidget(); $('#four').myWidget(); $('#one').myWidget('show'); //stuff from widget one is now visible $('#two').myWidget('show'); //stuff from widget one and two are now visible $('#three').myWidget('show'); //stuff from widget one, two and three are now visible $('#two').myWidget('hide'); //stuff from widget one and three are now visible $('#four').myWidget('show', {singular:true}); //stuff from widget four is now visible So, I imagine the show function looking like: show: function(options){ options = options || {}; if(options.singular){ var instances = '????'; // how do I get all instances? $.each(instances, function(i, o){ o.myWidget('hide'); }); } this.element.popover('show'); } So, question being, how would I get a reference to all elements that have the myWidget widget on them?

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• java annotations - problem with calling a locator class from a Vaadin Project

  - by George

  Hello, I'm not sure how to explain this without writing several pages so I hope the actual code is more expressive. I've made a jar containing multiple annotation declaration similar to the following: @Target(ElementType.PACKAGE) @Retention(RetentionPolicy.RUNTIME) public @interface MarkedPackage { } then I have made a test jar containing several classes in several packages and marked just one package with the above annotation (with package-info.java) like below: @myPackage.MarkedPackage package package.test.jar; this jar had in its build path the jar containing the annotations. then I made a static class that has a method (LoadPlugins) that retrieves a list with all the jars of a directory. Then it searches through the jars for the 'package-info' class and checks if that classes package contains the MarkedPackage annotation. by calling this: if (checkPackageAnnotation(thisClass.getPackage())) where thisClass is the package-info class retrieved via a classloader. and: public static boolean checkPackageAnnotation(AnnotatedElement elem) { System.out.println(elem.getAnnotations().length); if (elem == null || !elem.isAnnotationPresent(MarkedPackage.class)) return false; return true; } the elem.getAnnotatios().length is there for debug purposes. And the problem appears when I call the method from the static class: if I call it from a main function: public class MyMain { public static void main(String[] args){ PluginUtils.LoadPlugins(); } } everything works perfectly it displays '1' from that System.out.println(elem.getAnnotations().length); But if I call it from a button from my Vaadin project: header.addComponent(new Button("CallThat", new Button.ClickListener() { public void buttonClick(ClickEvent event) { PluginUtils.LoadPlugins(); } })); It displays '0' from that System.out.println(elem.getAnnotations().length); Also I should mention that I created the main inside my Vaadin project so it would have the exact same build path and resources. Is there a problem with web applications and that "@Retention(RetentionPolicy.RUNTIME)" ? hope I was clear enough... Hope someone has a solution for me... If you need more information - let me know. Thank you.

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• Best way to get a single value from a DataTable?

  - by PiersMyers

  I have a number of static classes that contain tables like this: using System; using System.Data; using System.Globalization; public static class TableFoo { private static readonly DataTable ItemTable; static TableFoo() { ItemTable = new DataTable("TableFoo") { Locale = CultureInfo.InvariantCulture }; ItemTable.Columns.Add("Id", typeof(int)); ItemTable.Columns["Id"].Unique = true; ItemTable.Columns.Add("Description", typeof(string)); ItemTable.Columns.Add("Data1", typeof(int)); ItemTable.Columns.Add("Data2", typeof(double)); ItemTable.Rows.Add(0, "Item 1", 1, 1.0); ItemTable.Rows.Add(1, "Item 2", 1, 1.0); ItemTable.Rows.Add(2, "Item 3", 2, 0.75); ItemTable.Rows.Add(3, "Item 4", 4, 0.25); ItemTable.Rows.Add(4, "Item 5", 1, 1.0); } public static DataTable GetItemTable() { return ItemTable; } public static int Data1(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (int)dr[0]["Data1"]; } public static double Data2(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (double)dr[0]["Data2"]; } } Is there a better way of writing the Data1 or Data2 methods that return a single value from a single row that matches the given id?

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• undefined reference to function, despite giving reference in c

  - by Jamie Edwards

  I'm following a tutorial, but when it comes to compiling and linking the code I get the following error: /tmp/cc8gRrVZ.o: In function `main': main.c:(.text+0xa): undefined reference to `monitor_clear' main.c:(.text+0x16): undefined reference to `monitor_write' collect2: ld returned 1 exit status make: *** [obj/main.o] Error 1 What that is telling me is that I haven't defined both 'monitor_clear' and 'monitor_write'. But I have, in both the header and source files. They are as follows: monitor.c: // monitor.c -- Defines functions for writing to the monitor. // heavily based on Bran's kernel development tutorials, // but rewritten for JamesM's kernel tutorials. #include "monitor.h" // The VGA framebuffer starts at 0xB8000. u16int *video_memory = (u16int *)0xB8000; // Stores the cursor position. u8int cursor_x = 0; u8int cursor_y = 0; // Updates the hardware cursor. static void move_cursor() { // The screen is 80 characters wide... u16int cursorLocation = cursor_y * 80 + cursor_x; outb(0x3D4, 14); // Tell the VGA board we are setting the high cursor byte. outb(0x3D5, cursorLocation >> 8); // Send the high cursor byte. outb(0x3D4, 15); // Tell the VGA board we are setting the low cursor byte. outb(0x3D5, cursorLocation); // Send the low cursor byte. } // Scrolls the text on the screen up by one line. static void scroll() { // Get a space character with the default colour attributes. u8int attributeByte = (0 /*black*/ << 4) | (15 /*white*/ & 0x0F); u16int blank = 0x20 /* space */ | (attributeByte << 8); // Row 25 is the end, this means we need to scroll up if(cursor_y >= 25) { // Move the current text chunk that makes up the screen // back in the buffer by a line int i; for (i = 0*80; i < 24*80; i++) { video_memory[i] = video_memory[i+80]; } // The last line should now be blank. Do this by writing // 80 spaces to it. for (i = 24*80; i < 25*80; i++) { video_memory[i] = blank; } // The cursor should now be on the last line. cursor_y = 24; } } // Writes a single character out to the screen. void monitor_put(char c) { // The background colour is black (0), the foreground is white (15). u8int backColour = 0; u8int foreColour = 15; // The attribute byte is made up of two nibbles - the lower being the // foreground colour, and the upper the background colour. u8int attributeByte = (backColour << 4) | (foreColour & 0x0F); // The attribute byte is the top 8 bits of the word we have to send to the // VGA board. u16int attribute = attributeByte << 8; u16int *location; // Handle a backspace, by moving the cursor back one space if (c == 0x08 && cursor_x) { cursor_x--; } // Handle a tab by increasing the cursor's X, but only to a point // where it is divisible by 8. else if (c == 0x09) { cursor_x = (cursor_x+8) & ~(8-1); } // Handle carriage return else if (c == '\r') { cursor_x = 0; } // Handle newline by moving cursor back to left and increasing the row else if (c == '\n') { cursor_x = 0; cursor_y++; } // Handle any other printable character. else if(c >= ' ') { location = video_memory + (cursor_y*80 + cursor_x); *location = c | attribute; cursor_x++; } // Check if we need to insert a new line because we have reached the end // of the screen. if (cursor_x >= 80) { cursor_x = 0; cursor_y ++; } // Scroll the screen if needed. scroll(); // Move the hardware cursor. move_cursor(); } // Clears the screen, by copying lots of spaces to the framebuffer. void monitor_clear() { // Make an attribute byte for the default colours u8int attributeByte = (0 /*black*/ << 4) | (15 /*white*/ & 0x0F); u16int blank = 0x20 /* space */ | (attributeByte << 8); int i; for (i = 0; i < 80*25; i++) { video_memory[i] = blank; } // Move the hardware cursor back to the start. cursor_x = 0; cursor_y = 0; move_cursor(); } // Outputs a null-terminated ASCII string to the monitor. void monitor_write(char *c) { int i = 0; while (c[i]) { monitor_put(c[i++]); } } void monitor_write_hex(u32int n) { s32int tmp; monitor_write("0x"); char noZeroes = 1; int i; for (i = 28; i > 0; i -= 4) { tmp = (n >> i) & 0xF; if (tmp == 0 && noZeroes != 0) { continue; } if (tmp >= 0xA) { noZeroes = 0; monitor_put (tmp-0xA+'a' ); } else { noZeroes = 0; monitor_put( tmp+'0' ); } } tmp = n & 0xF; if (tmp >= 0xA) { monitor_put (tmp-0xA+'a'); } else { monitor_put (tmp+'0'); } } void monitor_write_dec(u32int n) { if (n == 0) { monitor_put('0'); return; } s32int acc = n; char c[32]; int i = 0; while (acc > 0) { c[i] = '0' + acc%10; acc /= 10; i++; } c[i] = 0; char c2[32]; c2[i--] = 0; int j = 0; while(i >= 0) { c2[i--] = c[j++]; } monitor_write(c2); } monitor.h: // monitor.h -- Defines the interface for monitor.h // From JamesM's kernel development tutorials. #ifndef MONITOR_H #define MONITOR_H #include "common.h" // Write a single character out to the screen. void monitor_put(char c); // Clear the screen to all black. void monitor_clear(); // Output a null-terminated ASCII string to the monitor. void monitor_write(char *c); #endif // MONITOR_H common.c: // common.c -- Defines some global functions. // From JamesM's kernel development tutorials. #include "common.h" // Write a byte out to the specified port. void outb ( u16int port, u8int value ) { asm volatile ( "outb %1, %0" : : "dN" ( port ), "a" ( value ) ); } u8int inb ( u16int port ) { u8int ret; asm volatile ( "inb %1, %0" : "=a" ( ret ) : "dN" ( port ) ); return ret; } u16int inw ( u16int port ) { u16int ret; asm volatile ( "inw %1, %0" : "=a" ( ret ) : "dN" ( port ) ); return ret; } // Copy len bytes from src to dest. void memcpy(u8int *dest, const u8int *src, u32int len) { const u8int *sp = ( const u8int * ) src; u8int *dp = ( u8int * ) dest; for ( ; len != 0; len-- ) *dp++ =*sp++; } // Write len copies of val into dest. void memset(u8int *dest, u8int val, u32int len) { u8int *temp = ( u8int * ) dest; for ( ; len != 0; len-- ) *temp++ = val; } // Compare two strings. Should return -1 if // str1 < str2, 0 if they are equal or 1 otherwise. int strcmp(char *str1, char *str2) { int i = 0; int failed = 0; while ( str1[i] != '\0' && str2[i] != '\0' ) { if ( str1[i] != str2[i] ) { failed = 1; break; } i++; } // Why did the loop exit? if ( ( str1[i] == '\0' && str2[i] != '\0' || (str1[i] != '\0' && str2[i] =='\0' ) ) failed =1; return failed; } // Copy the NULL-terminated string src into dest, and // return dest. char *strcpy(char *dest, const char *src) { do { *dest++ = *src++; } while ( *src != 0 ); } // Concatenate the NULL-terminated string src onto // the end of dest, and return dest. char *strcat(char *dest, const char *src) { while ( *dest != 0 ) { *dest = *dest++; } do { *dest++ = *src++; } while ( *src != 0 ); return dest; } common.h: // common.h -- Defines typedefs and some global functions. // From JamesM's kernel development tutorials. #ifndef COMMON_H #define COMMON_H // Some nice typedefs, to standardise sizes across platforms. // These typedefs are written for 32-bit x86. typedef unsigned int u32int; typedef int s32int; typedef unsigned short u16int; typedef short s16int; typedef unsigned char u8int; typedef char s8int; void outb ( u16int port, u8int value ); u8int inb ( u16int port ); u16int inw ( u16int port ); #endif //COMMON_H main.c: // main.c -- Defines the C-code kernel entry point, calls initialisation routines. // Made for JamesM's tutorials <www.jamesmolloy.co.uk> #include "monitor.h" int main(struct multiboot *mboot_ptr) { monitor_clear(); monitor_write ( "hello, world!" ); return 0; } here is my makefile: C_SOURCES= main.c monitor.c common.c S_SOURCES= boot.s C_OBJECTS=$(patsubst %.c, obj/%.o, $(C_SOURCES)) S_OBJECTS=$(patsubst %.s, obj/%.o, $(S_SOURCES)) CFLAGS=-nostdlib -nostdinc -fno-builtin -fno-stack-protector -m32 -Iheaders LDFLAGS=-Tlink.ld -melf_i386 --oformat=elf32-i386 ASFLAGS=-felf all: kern/kernel .PHONY: clean clean: -rm -f kern/kernel kern/kernel: $(S_OBJECTS) $(C_OBJECTS) ld $(LDFLAGS) -o $@ $^ $(C_OBJECTS): obj/%.o : %.c gcc $(CFLAGS) $< -o $@ vpath %.c source $(S_OBJECTS): obj/%.o : %.s nasm $(ASFLAGS) $< -o $@ vpath %.s asem Hopefully this will help you understand what is going wrong and how to fix it :L Thanks in advance. Jamie.

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• How to detect the error raised on a particular codeline?

  - by infant programmer

  [Please edit the title if you find its not good enough] I have code which triggers XSL-transformation: objMemoryStream = new MemoryStream(); xslTransform = new XslCompiledTransform(); xpathXmlOrig = new XPathDocument("E:\\xslt error\\Simulation_of_error\\input.xml"); xslSettings = new XsltSettings(); xslSettings.EnableScript = true; xslTransform.Load(strXmlQueryTransformPath, xslSettings, new XmlUrlResolver()); xslTransform.Transform(xpathXmlOrig, null, objMemoryStream); objMemoryStream.Position = 0; StreamReader objStreamReader = new StreamReader(objMemoryStream); The method xslTransform.Load(strXmlQueryTransformPath, xslSettings, new XmlUrlResolver()); is a victim, which fails some times due to some time-out issue. I want to detect the failure of this codeline and execute again until it successfully executes! I tried using "TRY CATCH and WHILE methods": bool flag = true; do { try { xslTransform.Load(strXmlQueryTransformPath, xslSettings, new XmlUrlResolver()); flag = false; } catch { flag = true; } } while (flag); but the problem is "error is getting logged in the log file", Well. The whole code is under one more try statement, which I suspect is writing to log. Which is what I don't want... I don't want end user to know about the failure of this codeline. Is there anyway to get it done?

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• Atomic int writes on file

  - by Waneck

  Hello! I'm writing an application that will have to be able to handle many concurrent accesses to it, either by threads as by processes. So no mutex'es or locks should be applied to this. To make the use of locks go down to a minimum, I'm designing for the file to be "append-only", so all data is first appended to disk, and then the address pointing to the info it has updated, is changed to refer to the new one. So I will need to implement a small lock system only to change this one int so it refers to the new address. How is the best way to do it? I was thinking about maybe putting a flag before the address, that when it's set, the readers will use a spin lock until it's released. But I'm afraid that it isn't at all atomic, is it? e.g. a reader reads the flag, and it is unset on the same time, a writer writes the flag and changes the value of the int the reader may read an inconsistent value! I'm looking for locking techniques but all I find is either for thread locking techniques, or to lock an entire file, not fields. Is it not possible to do this? How do append-only databases handle this? Thanks! Cauê

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• Turning off antialiasing in Löve2D

  - by cjanssen

  I'm using Löve2D for writing a small game. Löve2D is an open source game engine for Lua. The problem I'm encountering is that some antialias filter is automatically applied to your sprites when you draw it at non-integer positions. love.graphics.draw( sprite, x, y ) So when x or y is not round (for example, x=100.24), the sprite appears blurred. The same happens when the sprite size is not even, because (x,y) points to the center of the sprite. For example, a sprite which is 31x30 big will appear blurred again, because its pixels are painted in non-integer positions. Since I am using pixel art, I want to avoid this all the way, otherwise the art is destroyed by this effect. The workaround I am using so far is to force the coordinates to be round by littering the code with calls to math.floor(), and forcing all the sprites to have even sizes by adding a row or column of transparent pixels with the paint program, if needed. Is there some command to deactivate the antialiasing I can call at program startup?

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• How to get the actual address of a pointer in C?

  - by Airjoe

  BACKGROUND: I'm writing a single level cache simulator in C for a homework assignment, and I've been given code that I must work from. In our discussions of the cache, we were told that the way a small cache can hold large addresses is by splitting the large address into the position in the cache and an identifying tag. That is, if you had an 8 slot cache but wanted to store something with address larger than 8, you take the 3 (because 2^3=8) rightmost bits and put the data in that position; so if you had address 22 for example, binary 10110, you would take those 3 rightmost bits 110, which is decimal 5, and put it in slot 5 of the cache. You would also store in this position the tag, which is the remaining bits 10. One function, cache_load, takes a single argument, and integer pointer. So effectively, I'm being given this int* addr which is an actual address and points to some value. In order to store this value in the cache, I need to split the addr. However, the compiler doesn't like when I try to work with the pointer directly. So, for example, I try to get the position by doing: npos=addr%num_slots The compiler gets angry and gives me errors. I tried casting to an int, but this actually got me the value that the pointer was pointing to, not the numerical address itself. Any help is appreciated, thanks!

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• ListBox Items Not Visible after DataBinding

  - by SidC

  Good Evening All, I am writing a page that allows users to search a parts table, select quantities and a listbox is to be populated with gridview values. Here's a snippet of my aspx page: <asp:ListBox runat="server" ID="lbItems" Width="155px"> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> </asp:ListBox> Here's the relevant contents of codebehind: Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 'Define DataTable Columns as incoming gridview fields Dim dtSelParts As DataTable = New DataTable Dim dr As DataRow = dtSelParts.NewRow() dtSelParts.Columns.Add("PartNumber") dtSelParts.Columns.Add("NSN") dtSelParts.Columns.Add("PartName") dtSelParts.Columns.Add("Qty") 'Select those gridview rows that have txtQty <> 0 For Each row As GridViewRow In MySearch.Rows Dim textboxText As String = _ CType(row.FindControl("txtQty"), TextBox).Text If textboxText <> "0" Then 'Create the row dr = dtSelParts.NewRow() 'Fill the row with data dr("PartNumber") = MySearch.DataKeys(row.RowIndex)("PartNumber") dr("NSN") = MySearch.DataKeys(row.RowIndex)("NSN") dr("PartName") = MySearch.DataKeys(row.RowIndex)("PartName") 'Add the row to the table dtSelParts.Rows.Add(dr) End If Next 'Need to send items to Listbox control lbItems lbItems.DataSource = New DataView(dtSelParts) lbItems.DataValueField = "PartNumber" lbItems.DataValueField = "NSN" lbItems.DataValueField = "PartName" lbItems.DataBind() End Sub The page runs fine in that my search functiobnality is intact, and I can input quantity values into my gridview's textbox. When I click Add to Quote the Listbox receives focus, but no list items are visible. I've created several list items in the aspx page, however I don't know how to populate the contents of my datatable in the listbox. Can someone help a newbie with this, seemingly, easy issue? Thanks, Sid

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