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• The Microsoft Ajax Library and Visual Studio Beta 2

  - by Stephen Walther

  Visual Studio 2010 Beta 2 was released this week and one of the first things that I hope you notice is that it no longer contains the latest version of ASP.NET AJAX. What happened? Where did AJAX go? Just like Sting and The Police, just like Phil Collins and Genesis, just like Greg Page and the Wiggles, AJAX has gone out of band! We are starting a solo career. A Name Change First things first. In previous releases, our Ajax framework was named ASP.NET AJAX. We now have changed the name of the framework to the Microsoft Ajax Library. There are two reasons behind this name change. First, the members of the Ajax team got tired of explaining to everyone that our Ajax framework is not tied to the server-side ASP.NET framework. You can use the Microsoft Ajax Library with ASP.NET Web Forms, ASP.NET MVC, PHP, Ruby on RAILS, and even pure HTML applications. Our framework can be used as a client-only framework and having the word ASP.NET in our name was confusing people. Second, it was time to start spelling the word Ajax like everyone else. Notice that the name is the Microsoft Ajax Library and not the Microsoft AJAX library. Originally, Microsoft used upper case AJAX because AJAX originally was an acronym for Asynchronous JavaScript and XML. And, according to Strunk and Wagnell, acronyms should be all uppercase. However, Ajax is one of those words that have migrated from acronym status to “just a word” status. So whenever you hear one of your co-workers talk about ASP.NET AJAX, gently correct your co-worker and say “It is now called the Microsoft Ajax Library.” Why OOB? But why move out-of-band (OOB)? The short answer is that we have had approximately 6 preview releases of the Microsoft Ajax Library over the last year. That’s a lot. We pride ourselves on being agile. Client-side technology evolves quickly. We want to be able to get a preview version of the Microsoft Ajax Library out to our customers, get feedback, and make changes to the library quickly. Shipping the Microsoft Ajax Library out-of-band keeps us agile and enables us to continue to ship new versions of the library even after ASP.NET 4 ships. Showing Love for JavaScript Developers One area in which we have received a lot of feedback is around making the Microsoft Ajax Library easier to use for developers who are comfortable with JavaScript. We also wanted to make it easy for jQuery developers to take advantage of the innovative features of the Microsoft Ajax Library. To achieve these goals, we’ve added the following features to the Microsoft Ajax Library (these features are included in the latest preview release that you can download right now): A simplified imperative syntax – We wanted to make it brain-dead simple to create client-side Ajax controls when writing JavaScript. A client script loader – We wanted the Microsoft Ajax Library to load all of the scripts required by a component or control automatically. jQuery integration – We love the jQuery selector syntax. We wanted to make it easy for jQuery developers to use the Microsoft Ajax Library without changing their programming style. If you are interested in learning about these new features of the Microsoft Ajax Library, I recommend that you read the following blog post by Scott Guthrie: http://weblogs.asp.net/scottgu/archive/2009/10/15/announcing-microsoft-ajax-library-preview-6-and-the-microsoft-ajax-minifier.aspx Downloading the Latest Version of the Microsoft Ajax Library Currently, the best place to download the latest version of the Microsoft Ajax Library is directly from the ASP.NET CodePlex project: http://aspnet.codeplex.com/ As I write this, the current version is Preview 6. The next version is coming out at the PDC. Summary I’m really excited about the future of the Microsoft Ajax Library. Moving outside of the ASP.NET framework provides us the flexibility to remain agile and continue to innovate aggressively. The latest preview release of the Microsoft Ajax Library includes several major new features including a client script loader, jQuery integration, and a simplified client control creation syntax.

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• Why you need to learn async in .NET

  - by PSteele

  I had an opportunity to teach a quick class yesterday about what’s new in .NET 4.0.  One of the topics was the TPL (Task Parallel Library) and how it can make async programming easier.  I also stressed that this is the direction Microsoft is going with for C# 5.0 and learning the TPL will greatly benefit their understanding of the new async stuff.  We had a little time left over and I was able to show some code that uses the Async CTP to accomplish some stuff, but it wasn’t a simple demo that you could jump in to and understand so I thought I’d thrown one together and put it in a blog post. The entire solution file with all of the sample projects is located here. A Simple Example Let’s start with a super-simple example (WindowsApplication01 in the solution). I’ve got a form that displays a label and a button.  When the user clicks the button, I want to start displaying the current time for 15 seconds and then stop. What I’d like to write is this: lblTime.ForeColor = Color.Red; for (var x = 0; x < 15; x++) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); Thread.Sleep(1000); } lblTime.ForeColor = SystemColors.ControlText; (Note that I also changed the label’s color while counting – not quite an ILM-level effect, but it adds something to the demo!) As I’m sure most of my readers are aware, you can’t write WinForms code this way.  WinForms apps, by default, only have one thread running and it’s main job is to process messages from the windows message pump (for a more thorough explanation, see my Visual Studio Magazine article on multithreading in WinForms).  If you put a Thread.Sleep in the middle of that code, your UI will be locked up and unresponsive for those 15 seconds.  Not a good UX and something that needs to be fixed.  Sure, I could throw an “Application.DoEvents()” in there, but that’s hacky. The Windows Timer Then I think, “I can solve that.  I’ll use the Windows Timer to handle the timing in the background and simply notify me when the time has changed”.  Let’s see how I could accomplish this with a Windows timer (WindowsApplication02 in the solution): public partial class Form1 : Form { private readonly Timer clockTimer; private int counter;   public Form1() { InitializeComponent(); clockTimer = new Timer {Interval = 1000}; clockTimer.Tick += UpdateLabel; }   private void UpdateLabel(object sender, EventArgs e) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); counter++; if (counter == 15) { clockTimer.Enabled = false; lblTime.ForeColor = SystemColors.ControlText; } }   private void cmdStart_Click(object sender, EventArgs e) { lblTime.ForeColor = Color.Red; counter = 0; clockTimer.Start(); } } Holy cow – things got pretty complicated here.  I use the timer to fire off a Tick event every second.  Inside there, I can update the label.  Granted, I can’t use a simple for/loop and have to maintain a global counter for the number of iterations.  And my “end” code (when the loop is finished) is now buried inside the bottom of the Tick event (inside an “if” statement).  I do, however, get a responsive application that doesn’t hang or stop repainting while the 15 seconds are ticking away. But doesn’t .NET have something that makes background processing easier? The BackgroundWorker Next I try .NET’s BackgroundWorker component – it’s specifically designed to do processing in a background thread (leaving the UI thread free to process the windows message pump) and allows updates to be performed on the main UI thread (WindowsApplication03 in the solution): public partial class Form1 : Form { private readonly BackgroundWorker worker;   public Form1() { InitializeComponent(); worker = new BackgroundWorker {WorkerReportsProgress = true}; worker.DoWork += StartUpdating; worker.ProgressChanged += UpdateLabel; worker.RunWorkerCompleted += ResetLabelColor; }   private void StartUpdating(object sender, DoWorkEventArgs e) { var workerObject = (BackgroundWorker) sender; for (int x = 0; x < 15; x++) { workerObject.ReportProgress(0); Thread.Sleep(1000); } }   private void UpdateLabel(object sender, ProgressChangedEventArgs e) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); }   private void ResetLabelColor(object sender, RunWorkerCompletedEventArgs e) { lblTime.ForeColor = SystemColors.ControlText; }   private void cmdStart_Click(object sender, EventArgs e) { lblTime.ForeColor = Color.Red; worker.RunWorkerAsync(); } } Well, this got a little better (I think).  At least I now have my simple for/next loop back.  Unfortunately, I’m still dealing with event handlers spread throughout my code to co-ordinate all of this stuff in the right order. Time to look into the future. The async way Using the Async CTP, I can go back to much simpler code (WindowsApplication04 in the solution): private async void cmdStart_Click(object sender, EventArgs e) { lblTime.ForeColor = Color.Red; for (var x = 0; x < 15; x++) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); await TaskEx.Delay(1000); } lblTime.ForeColor = SystemColors.ControlText; } This code will run just like the Timer or BackgroundWorker versions – fully responsive during the updates – yet is way easier to implement.  In fact, it’s almost a line-for-line copy of the original version of this code.  All of the async plumbing is handled by the compiler and the framework.  My code goes back to representing the “what” of what I want to do, not the “how”. I urge you to download the Async CTP.  All you need is .NET 4.0 and Visual Studio 2010 sp1 – no need to set up a virtual machine with the VS2011 beta (unless, of course, you want to dive right in to the C# 5.0 stuff!).  Starting playing around with this today and see how much easier it will be in the future to write async-enabled applications.

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• Stepping outside Visual Studio IDE [Part 2 of 2] with Mono 2.6.4

  - by mbcrump

  Continuing part 2 of my Stepping outside the Visual Studio IDE, is the open-source Mono Project. Mono is a software platform designed to allow developers to easily create cross platform applications. Sponsored by Novell (http://www.novell.com/), Mono is an open source implementation of Microsoft's .NET Framework based on the ECMA standards for C# and the Common Language Runtime. A growing family of solutions and an active and enthusiastic contributing community is helping position Mono to become the leading choice for development of Linux applications. So, to clarify. You can use Mono to develop .NET applications that will run on Linux, Windows or Mac. It’s basically a IDE that has roots in Linux. Let’s first look at the compatibility: Compatibility If you already have an application written in .Net, you can scan your application with the Mono Migration Analyzer (MoMA) to determine if your application uses anything not supported by Mono. The current release version of Mono is 2.6. (Released December 2009) The easiest way to describe what Mono currently supports is: Everything in .NET 3.5 except WPF and WF, limited WCF. Here is a slightly more detailed view, by .NET framework version: Implemented C# 3.0 System.Core LINQ ASP.Net 3.5 ASP.Net MVC C# 2.0 (generics) Core Libraries 2.0: mscorlib, System, System.Xml ASP.Net 2.0 - except WebParts ADO.Net 2.0 Winforms/System.Drawing 2.0 - does not support right-to-left C# 1.0 Core Libraries 1.1: mscorlib, System, System.Xml ASP.Net 1.1 ADO.Net 1.1 Winforms/System.Drawing 1.1 Partially Implemented LINQ to SQL - Mostly done, but a few features missing WCF - silverlight 2.0 subset completed Not Implemented WPF - no plans to implement WF - Will implement WF 4 instead on future versions of Mono. System.Management - does not map to Linux System.EnterpriseServices - deprecated Links to documentation. The Official Mono FAQ’s Links to binaries. Mono IDE Latest Version is 2.6.4 That's it, nothing more is required except to compile and run .net code in Linux. Installation After landing on the mono project home page, you can select which platform you want to download. I typically pick the Virtual PC image since I spend all of my day using Windows 7. Go ahead and pick whatever version is best for you. The Virtual PC image comes with Suse Linux. Once the image is launch, you will see the following: I’m not going to go through each option but its best to start with “Start Here” icon. It will provide you with information on new projects or existing VS projects. After you get Mono installed, it's probably a good idea to run a quick Hello World program to make sure everything is setup properly. This allows you to know that your Mono is working before you try writing or running a more complex application. To write a "Hello World" program follow these steps: Start Mono Development Environment. Create a new Project: File->New->Solution Select "Console Project" in the category list. Enter a project name into the Project name field, for example, "HW Project". Click "Forward" Click “Packaging” then OK. You should have a screen very simular to a VS Console App. Click the "Run" button in the toolbar (Ctrl-F5). Look in the Application Output and you should have the “Hello World!” Your screen should look like the screen below. That should do it for a simple console app in mono. To test out an ASP.NET application, simply copy your code to a new directory in /srv/www/htdocs, then visit the following URL: http://localhost/directoryname/page.aspx where directoryname is the directory where you deployed your application and page.aspx is the initial page for your software. Databases You can continue to use SQL server database or use MySQL, Postgress, Sybase, Oracle, IBM’s DB2 or SQLite db. Conclusion I hope this brief look at the Mono IDE helps someone get acquainted with development outside of VS. As always, I welcome any suggestions or comments.

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• SQL Management Studio is painfully slow on 32-bit Windows 7

  - by Sergei

  I've been having issues running anything in SQL Management Studio on Win 7. Basically, doing anything through the Management Studio interfaces completely freezes it up for a few minutes. Running a query is nearly impossible because it takes nearly 2 minutes just for the IDE to parse it and another minute to run it when the query itself completes instantaneously outside of the IDE. I'm not even going to go into the query designer. Anything with heavy user interaction such as editing a row in the result set where i have to click a cell freezes up the front-end. I tried reinstalling to no avail. Also tried running in compatibility mode without any difference whatsoever. Anybody had a similar experience? I'm running SQL Management Studio 2008 version 10.0.2531.0 on 32-bit Windows 7. Connecting to a remote SQL Server instance (2008 R2). Thanks.

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• Visual Studio Development on Virtual Box, Boot Camp, or VMWare Fusion

  - by Eli

  I currently have a Mac, 2ghz and 2 gigs of ram, running OS X Leopard and Virtual Box with a Windows 7 Pro 32bit virtual machine. Performance on the virtual machine is fine for minor tasks but is very clunky while trying to multi-task or develop in Visual Studio 2008. What would be my best option for being able to use Visual Studio, keeping cost and time in mind? 1) Upgrade ram to 4 gigs ($100). Will this really improve my performance enough to use Visual Studio in a Windows 7 vm? Or am I just wasting time/money? 2) Reinstall/restore Windows 7 disk image as a Boot Camp partition. I assume this should improve my performance, yes? 3) Purchase VMWare fusion instead of VirtualBox. Does Fusion require less resources to run? I am open to any suggestions. Thanks in advance

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• Stumbling Through: Visual Studio 2010 (Part II)

  I would now like to expand a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on a few other features of VS 2010.  Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source.  Im not going to take the easy way and tie to a SQL Server data source, though, I will tie it to an XML data file instead.  Why?  Well, why not?  This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down a path less travelled and maybe learn a few things along the way.  Once we get this XML data and the means to interact with it, I will revisit data binding to this data in a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly with minimal code.  To begin, I will use what was learned in the first part of this blog topic and draw out a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article.  The data model looks as follows, with Teams having Players, and Players having a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position.  The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team>     <Player>         <Statistic/>     </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent.  Position, however, is more of a lookup value that will not have any hierarchical relationship to the player.  In fact, the Position data itself may be in a completely different xml file (something Id like to play around with), so in any case, a player will need to reference the position by its Id. So now that we have a simple data model laid out, I would like to generate two things based on it:  A class for each entity with properties corresponding to each entity property An IO class with methods to get data for each entity, either all instances, by Id or by parent. Now my experience with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith).  Surely, there has got to be a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support.  Lets start with that built-in stuff to give us a base to work off of.  Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite a bit towards what I was intending: It apparently generated a class for each entity, but also a whole ton more.  I mean a TON more.  Way too much complicated code was generated now that code is likely to be a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing!  That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog.  Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids).  Using the Extension Manager (Available under the Tools menu), I did a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was a breeze, and after doing so I got some color coding and intellisense while editing the tt files.  If you will be doing any customizing of tt files, I highly recommend installing this extension.  Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Asynchrony in C# 5 (Part II)

  - by javarg

  This article is a continuation of the series of asynchronous features included in the new Async CTP preview for next versions of C# and VB. Check out Part I for more information. So, let’s continue with TPL Dataflow: Asynchronous functions TPL Dataflow Task based asynchronous Pattern Part II: TPL Dataflow Definition (by quote of Async CTP doc): “TPL Dataflow (TDF) is a new .NET library for building concurrent applications. It promotes actor/agent-oriented designs through primitives for in-process message passing, dataflow, and pipelining. TDF builds upon the APIs and scheduling infrastructure provided by the Task Parallel Library (TPL) in .NET 4, and integrates with the language support for asynchrony provided by C#, Visual Basic, and F#.” This means: data manipulation processed asynchronously. “TPL Dataflow is focused on providing building blocks for message passing and parallelizing CPU- and I/O-intensive applications”. Data manipulation is another hot area when designing asynchronous and parallel applications: how do you sync data access in a parallel environment? how do you avoid concurrency issues? how do you notify when data is available? how do you control how much data is waiting to be consumed? etc.  Dataflow Blocks TDF provides data and action processing blocks. Imagine having preconfigured data processing pipelines to choose from, depending on the type of behavior you want. The most basic block is the BufferBlock<T>, which provides an storage for some kind of data (instances of <T>). So, let’s review data processing blocks available. Blocks a categorized into three groups: Buffering Blocks Executor Blocks Joining Blocks Think of them as electronic circuitry components :).. 1. BufferBlock<T>: it is a FIFO (First in First Out) queue. You can Post data to it and then Receive it synchronously or asynchronously. It synchronizes data consumption for only one receiver at a time (you can have many receivers but only one will actually process it). 2. BroadcastBlock<T>: same FIFO queue for messages (instances of <T>) but link the receiving event to all consumers (it makes the data available for consumption to N number of consumers). The developer can provide a function to make a copy of the data if necessary. 3. WriteOnceBlock<T>: it stores only one value and once it’s been set, it can never be replaced or overwritten again (immutable after being set). As with BroadcastBlock<T>, all consumers can obtain a copy of the value. 4. ActionBlock<TInput>: this executor block allows us to define an operation to be executed when posting data to the queue. Thus, we must pass in a delegate/lambda when creating the block. Posting data will result in an execution of the delegate for each data in the queue. You could also specify how many parallel executions to allow (degree of parallelism). 5. TransformBlock<TInput, TOutput>: this is an executor block designed to transform each input, that is way it defines an output parameter. It ensures messages are processed and delivered in order. 6. TransformManyBlock<TInput, TOutput>: similar to TransformBlock but produces one or more outputs from each input. 7. BatchBlock<T>: combines N single items into one batch item (it buffers and batches inputs). 8. JoinBlock<T1, T2, …>: it generates tuples from all inputs (it aggregates inputs). Inputs could be of any type you want (T1, T2, etc.). 9. BatchJoinBlock<T1, T2, …>: aggregates tuples of collections. It generates collections for each type of input and then creates a tuple to contain each collection (Tuple<IList<T1>, IList<T2>>). Next time I will show some examples of usage for each TDF block. * Images taken from Microsoft’s Async CTP documentation.

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• Stumbling Through: Visual Studio 2010 (Part II)

  I would now like to expand a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on a few other features of VS 2010.  Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source.  Im not going to take the easy way and tie to a SQL Server data source, though, I will tie it to an XML data file instead.  Why?  Well, why not?  This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down a path less travelled and maybe learn a few things along the way.  Once we get this XML data and the means to interact with it, I will revisit data binding to this data in a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly with minimal code.  To begin, I will use what was learned in the first part of this blog topic and draw out a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article.  The data model looks as follows, with Teams having Players, and Players having a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position.  The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team>     <Player>         <Statistic/>     </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent.  Position, however, is more of a lookup value that will not have any hierarchical relationship to the player.  In fact, the Position data itself may be in a completely different xml file (something Id like to play around with), so in any case, a player will need to reference the position by its Id. So now that we have a simple data model laid out, I would like to generate two things based on it:  A class for each entity with properties corresponding to each entity property An IO class with methods to get data for each entity, either all instances, by Id or by parent. Now my experience with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith).  Surely, there has got to be a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support.  Lets start with that built-in stuff to give us a base to work off of.  Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite a bit towards what I was intending: It apparently generated a class for each entity, but also a whole ton more.  I mean a TON more.  Way too much complicated code was generated now that code is likely to be a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing!  That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog.  Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids).  Using the Extension Manager (Available under the Tools menu), I did a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was a breeze, and after doing so I got some color coding and intellisense while editing the tt files.  If you will be doing any customizing of tt files, I highly recommend installing this extension.  Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Passing a parameter using RelayCommand defined in the ViewModel (from Josh Smith example)

  - by eesh

  I would like to pass a parameter defined in the XAML (View) of my application to the ViewModel class by using the RelayCommand. I followed Josh Smith's excellent article on MVVM and have implemented the following. XAML Code <Button Command="{Binding Path=ACommandWithAParameter}" CommandParameter="Orange" HorizontalAlignment="Left" Style="{DynamicResource SimpleButton}" VerticalAlignment="Top" Content="Button"/> ViewModel Code public RelayCommand _aCommandWithAParameter; /// <summary> /// Returns a command with a parameter /// </summary> public RelayCommand ACommandWithAParameter { get { if (_aCommandWithAParameter == null) { _aCommandWithAParameter = new RelayCommand( param => this.CommandWithAParameter("Apple") ); } return _aCommandWithAParameter; } } public void CommandWithAParameter(String aParameter) { String theParameter = aParameter; } #endregion I set a breakpoint in the CommandWithAParameter method and observed that aParameter was set to "Apple", and not "Orange". This seems obvious as the method CommandWithAParameter is being called with the literal String "Apple". However, looking up the execution stack, I can see that "Orange", the CommandParameter I set in the XAML is the parameter value for RelayCommand implemenation of the ICommand Execute interface method. That is the value of parameter in the method below of the execution stack is "Orange", public void Execute(object parameter) { _execute(parameter); } What I am trying to figure out is how to create the RelayCommand ACommandWithAParameter property such that it can call the CommandWithAParameter method with the CommandParameter "Orange" defined in the XAML. Is there a way to do this? Why do I want to do this? Part of "On The Fly Localization" In my particular implementation I want to create a SetLanguage RelayCommand that can be bound to multiple buttons. I would like to pass the two character language identifier ("en", "es", "ja", etc) as the CommandParameter and have that be defined for each "set language" button defined in the XAML. I want to avoid having to create a SetLanguageToXXX command for each language supporting and hard coding the two character language identifier into each RelayCommand in the ViewModel.

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• Why model => model.Reason_ID turns to model =>Convert(model.Reason_ID)

  - by er-v

  I have my own html helper extension, wich I use this way <%=Html.LocalizableLabelFor(model => model.Reason_ID, Register.PurchaseReason) %> which declared like this. public static MvcHtmlString LocalizableLabelFor<T>(this HtmlHelper<T> helper, Expression<Func<T, object>> expr, string captionValue) where T : class { return helper.LocalizableLabelFor(ExpressionHelper.GetExpressionText(expr), captionValue); } but when I open it in debugger expr.Body.ToString() will show me Convert(model.Reason_ID). But should model.Reason_ID. That's a big problem, becouse ExpressionHelper.GetExpressionText(expr) returns empty string. What a strange magic is that? How can I get rid of it?

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• How to prevent Project ASP.NET Configuration and Team Foundation Server from fighting

  - by Brian

  So, I am using visual studio 2005 (and team explorer 2005) with tfs 2008. I have installed both Visual Studio 2005 SP1 and VS80sp1-KB932544-X86-ENU.exe. I perform the following steps: Select Project-ASP.NET Configuration within Visual Studio 2005. Within Visual Studio 2005, attempt to perform either a check-in or a checkout. The following happens: The local server started by Visual Studio starts closing itself. I suspect it is crashing; the systray icons are not properly disposed of. It then reopens itself. It does this over and over again, maybe once every second or two. The TFS progress meter doesn't even budge, it just sits there. Canceling out of the checkout does not work; it says it is cancelling and does nothing. Any suggestions?

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• How can I use external expressions in Linq with EF4 (and LINQKit)?

  - by neo

  I want to separate out often used expressions in linq queries. I'm using Entity Framework 4 and also LINQKit but I still don't know how I should do it the right way. Let me give you an example: Article article = dataContainer.Articles.FirstOrDefault(a => a.Id == id); IEnumerable<Comment> comments = (from c in container.Comments where CommentExpressions.IsApproved.Invoke(c) select c); public static class CommentExpressions { public static Expression<Func<Module, bool>> IsApproved { get { return m => m.IsApproved; } } } Of course the IsApproved expression would be something much more complicated. The problem is that the Invoke() won't work because I didn't call .asExpandable() from LINQKit on container.Comments but I can't call it because it's just an ICollection instead of an ObjectSet. So my question is: Do I always have to go through the data context when I want to include external expressions or can I somehow use it on the object I fetched (Article)? Any ideas or best practices? Thanks very much! neo

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• Using antlr and the DLR together -- AST conversion

  - by RCIX

  I have an AST generated via ANTLR, and I need to convert it to a DLR-compatible one (Expression Trees). However, it would seem that i can't use tree pattern matchers for this as expression trees need their subtrees at instantiation (which i can't get). What solution would be best for me to use?

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• C# - closures over class fields inside an initializer?

  - by Richard Berg

  Consider the following code: using System; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { var square = new Square(4); Console.WriteLine(square.Calculate()); } } class MathOp { protected MathOp(Func<int> calc) { _calc = calc; } public int Calculate() { return _calc(); } private Func<int> _calc; } class Square : MathOp { public Square(int operand) : base(() => _operand * _operand) // runtime exception { _operand = operand; } private int _operand; } } (ignore the class design; I'm not actually writing a calculator! this code merely represents a minimal repro for a much bigger problem that took awhile to narrow down) I would expect it to either: print "16", OR throw a compile time error if closing over a member field is not allowed in this scenario Instead I get a nonsensical exception thrown at the indicated line. On the 3.0 CLR it's a NullReferenceException; on the Silverlight CLR it's the infamous Operation could destabilize the runtime.

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• Call asp.net mvc Html Helper within custom html helper with expression parameter

  - by Frank Michael Kraft

  I am trying to write an html helper extension within the asp.net mvc framework. public static MvcHtmlString PlatformNumericTextBoxFor<TModel>(this HtmlHelper instance, TModel model, Expression<Func<TModel,double>> selector) where TModel : TableServiceEntity { var viewModel = new PlatformNumericTextBox(); var func = selector.Compile(); MemberExpression memExpession = (MemberExpression)selector.Body; string name = memExpession.Member.Name; var message = instance.ValidationMessageFor<TModel, double>(selector); viewModel.name = name; viewModel.value = func(model); viewModel.validationMessage = String.Empty; var result = instance.Partial(typeof(PlatformNumericTextBox).Name, viewModel); return result; } The line var message = instance.ValidationMessageFor<TModel, double>(selector); has a syntax error. But I do not understand it. The error is: Fehler 2 "System.Web.Mvc.HtmlHelper" enthält keine Definition für "ValidationMessageFor", und die Überladung der optimalen Erweiterungsmethode "System.Web.Mvc.Html.ValidationExtensions.ValidationMessageFor(System.Web.Mvc.HtmlHelper, System.Linq.Expressions.Expression)" weist einige ungültige Argumente auf. C:\Projects\WorkstreamPlatform\WorkstreamPlatform_WebRole\Extensions\PlatformHtmlHelpersExtensions.cs 97 27 WorkstreamPlatform_WebRole So according to the message, the parameter is invalid. But the method is actually declared like this: public static MvcHtmlString ValidationMessageFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression); So actually it should work.

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• Javascript: Calling a function written in an anonymous function from String with the function's name

  - by Kai barry yuzanic

  Hello. I've started using jQuery and am wondering how to call functions in an anonymous function dynamically from String. Let's say for instance, I have the following functions: function foo() { // Being in the global namespace, // this function can be called with window['foo']() alert("foo"); } jQuery(document).ready(function(){ function bar() { // How can this function be called // by using a String of the function's name 'bar'?? alert("bar"); } // I want to call the function bar here from String with the name 'bar' } I've been trying to figure out what could be the counterpart of 'window', which can call functions from the global namespace such as window["foo"]. In the small example above, how I can call the function bar from a String "bar"? Thank you for your help.

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• How can I combine several Expressions into a fast method?

  - by chillitom

  Suppose I have the following expressions: Expression<Action<T, StringBuilder>> expr1 = (t, sb) => sb.Append(t.Name); Expression<Action<T, StringBuilder>> expr2 = (t, sb) => sb.Append(", "); Expression<Action<T, StringBuilder>> expr3 = (t, sb) => sb.Append(t.Description); I'd like to be able to compile these into a method/delegate equivalent to the following: void Method(T t, StringBuilder sb) { sb.Append(t.Name); sb.Append(", "); sb.Append(t.Description); } What is the best way to approach this? I'd like it to perform well, ideally with performance equivalent to the above method. UPDATE So, whilst it appears that there is no way to do this directly in C#3 is there a way to convert an expression to IL so that I can use it with System.Reflection.Emit?

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• Executing a modified expression

  - by Sam

  I found this brief demo: http://msdn.microsoft.com/en-us/library/bb546136.aspx Which discusses modifying an expression. However the code starts with a Expression<Func<string, bool>> and ends up with a Expression so it's not complete. How do I take that expression and make it typed as Expression<Func<string,bool>> again? All the examples I have have found on executing an expression all involve dynamically created expressions which is not what this case has. Here the original expression is defined at compile time. And the code I want to write to do this won't know much about the expression, ideally as little as possible. I definately can't see how I would know what "Paramaters" to pass to Expression.LambdaExpression... In my particular case I want to search for any references to a particular propery of type A and swap them out with a reference to a property of type B then pass the expression to a call to IEnumerable.Where. ie. p=>p.Name == "Sam" where P is Foo1 becomes p=>p.FirstName == "Sam" where p is Foo2

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• Dictionary<string,string> to Dictionary<Control,object> using IEnumerable<T>.Select()

  - by abatishchev

  I have a System.Collections.Generic.Dictionary<string, string> containing control ID and appropriate data column to data bind: var dic = new Dictionary<string, string> { { "Label1", "FooCount" }, { "Label2", "BarCount" } }; I use it that way: var row = ((DataRowView)FormView1.DataItem).Row; Dictionary<Control, object> newOne = dic.ToDictionary( k => FormView1.FindControl(k.Key)), k => row[k.Value]); So I'm using IEnumerable<T>.ToDictionary(Func<T>, Func<T>). Is it possbile to do the same using IEnumerable<T>.Select(Func<T>) ?

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• Linq to SQL DynamicInvoke(System.Object[])' has no supported translation to SQL.

  - by ewwwyn

  I have a class, Users. Users has a UserId property. I have a method that looks something like this: static IQueryable<User> FilterById(this IQueryable<User> p, Func<int, bool> sel) { return p.Where(m => sel(m)); } Inevitably, when I call the function: var users = Users.FilterById(m => m > 10); I get the following exception: Method 'System.Object DynamicInvoke(System.Object[])' has no supported translation to SQL. Is there any solution to this problem? How far down the rabbit hole of Expression.KillMeAndMyFamily() might I have to go? To clarify why I'm doing this: I'm using T4 templates to autogenerate a simple repository and a system of pipes. Within the pipes, instead of writing: new UserPipe().Where(m => m.UserId > 10 && m.UserName.Contains("oo") && m.LastName == "Wee"); I'd like to generate something like: new UserPipe() .UserId(m => m > 10) .UserName(m => m.Contains("oo")) .LastName("Wee");

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• Strongly typed API for ASP.NET MVC 2 async actions

  - by Alexey Zakharov

  Hi guys, Have anybody tried to create strongly typed API for ASP.NET MVC 2 async actions? Best regards, Alexey Zakharov

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• C++0x and the Lack of Polymorphic Lambdas - Why?

  - by Dominar

  I've been reviewing the draft version of the upcoming C++0x standard. Specifically the section on lambdas, and am confused as to the reasoning for not introducing polymorphic lambdas. I had hoped we could use code such as the following: template<typename Container> void foo(Container c) { for_each(c.begin(),c.end(),[](T& t) { ++t; }); } What were the reasons: Was it the committee ran out of time? That polymorphic lambdas are too hard to implement? Or perhaps that they are seen as not being needed by the PTB?

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• PHP sandbox/sanitize code passed to create_function

  - by kpowerinfinity

  Hello, I am using create_function to run some user-code at server end. I am looking for any of these two: Is there a way to sanitize the code passed to it to prevent something harmful from executing? Alternately, is there a way to specify this code to be run in a sandboxed environment so that the user can't play around with anything else. Thanks!

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• Undefined symbols for C++0x lambdas?

  - by Austin Hyde

  I was just poking around into some new stuff in C++0x, when I hit a stumbling block: #include <list> #include <cstdio> using namespace std; template <typename T,typename F> void ForEach (list<T> l, F f) { for (typename list<T>::iterator it=l.begin();it!=l.end();++it) f(*it); } int main() { int arr[] = {1,2,3,4,5,6}; list<int> l (arr,arr+6); ForEach(l,[](int x){printf("%d\n",x);}); } does not compile. I get a load of undefined symbol errors. Here's make's output: i386-apple-darwin9-gcc-4.5.0 -std=c++0x -I/usr/local/include -o func main.cpp Undefined symbols: "___cxa_rethrow", referenced from: std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o "operator new(unsigned long)", referenced from: __gnu_cxx::new_allocator<std::_List_node<int> >::allocate(unsigned long, void const*) in ccPxxPwU.o "___gxx_personality_v0", referenced from: ___gxx_personality_v0$non_lazy_ptr in ccPxxPwU.o "___cxa_begin_catch", referenced from: std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o "operator delete(void*)", referenced from: __gnu_cxx::new_allocator<std::_List_node<int> >::deallocate(std::_List_node<int>*, unsigned long) in ccPxxPwU.o "___cxa_end_catch", referenced from: std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o "std::__throw_bad_alloc()", referenced from: __gnu_cxx::new_allocator<std::_List_node<int> >::allocate(unsigned long, void const*) in ccPxxPwU.o "std::_List_node_base::_M_hook(std::_List_node_base*)", referenced from: void std::list<int, std::allocator<int> >::_M_insert<int const&>(std::_List_iterator<int>, int const&&&) in ccPxxPwU.o ld: symbol(s) not found collect2: ld returned 1 exit status make: *** [func] Error 1 Why is this not working?

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• Problem in populating a dictionary using Enumerable.Range()

  - by Newbie

  If I do for (int i = 0; i < appSettings.Count; i++) { string key = appSettings.Keys[i]; euFileDictionary.Add(key, appSettings[i]); } It is working fine. When I am trying the same thing using Enumerable.Range(0, appSettings.Count).Select(i => { string Key = appSettings.Keys[i]; string Value = appSettings[i]; euFileDictionary.Add(Key, Value); }).ToDictionary<string,string>(); I am getting a compile time error The type arguments for method 'System.Linq.Enumerable.Select(System.Collections.Generic.IEnumerable, System.Func)' cannot be inferred from the usage. Try specifying the type arguments explicitly. Any idea? Using C#3.0 Thanks

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