Kodefu

ref on Reference Type?!

Chris Eargle — Fri, 12 Jun 2009 21:30:06 GMT

I recently came across a piece of code that had almost every parameter for every method marked with the ref keyword. This keyword is primarily used to pass a value type by reference, but this one even had reference types marked with the keyword. This made me wonder, why exactly would you ever want to pass a reference type as a ref parameter?

Refactor to Array Initializer

Chris Eargle — Wed, 10 Jun 2009 17:39:39 GMT

Taking advantage of language features can make sleeker, easier to maintain code. One of these language features are array initializers.

Have you ever created an array, then assigned each element in the array? This incurs many lines of code with no tangible benefit. Check out this code from the NameMangler class in LINQ to XSD.

Read More

Structs Structs Structs

Chris Eargle — Mon, 08 Jun 2009 18:31:35 GMT

It appears that my blog post on Friday wasn't saved. This is kind of bizarre. You can catch back up on it at my website.

Stop Using Structs Everywhere

And I posted a follow-up today:

DynamicAttribute

Chris Eargle — Thu, 04 Jun 2009 22:18:44 GMT

We've all been told to think of a dynamic object as a regular object but with dynamic behavior. Kevin Hazzard peeked behind the curtain to show that the compiler is actually doing a lot with that keyword; it isn't just an object. It does change the type to an object, but then it builds CallSites everywhere that object is referenced. These CallSites handle the calls to the dynamic language runtime.

That's great, but we have an object. How does a consumer of your class library know that a property you marked as dynamic is dynamic when it is compiled to an object? To figure this out, I compiled a simple class then reflected it.

    public class TestDynamic

    {

        public dynamic Foo { get; set; }

        public void Bar()

        {

            Console.WriteLine(Foo);

        }

    }

I refactored the reflected class to make it easier to read.

    public class TestManual

    {

        [Dynamic]

        private object k__BackingField;

        public void Bar()

        {

            if (SiteContainer.Site1 == null)

            {

                SiteContainer.Site1 = CallSite<Action<CallSite, Type, object>>.Create(new CSharpInvokeMemberBinder(CSharpCallFlags.None, "WriteLine", typeof(TestDynamic), null, new CSharpArgumentInfo[] { new CSharpArgumentInfo(CSharpArgumentInfoFlags.IsStaticType | CSharpArgumentInfoFlags.UseCompileTimeType, null), new CSharpArgumentInfo(CSharpArgumentInfoFlags.None, null) }));

            }

            SiteContainer.Site1.Target(SiteContainer.Site1, typeof(Console), this.Foo);

        }

        [Dynamic]

        public object Foo { [return: Dynamic] get; [param: Dynamic] set; }

        private static class SiteContainer

        {

            public static CallSite<Action<CallSite, Type, object>> Site1;

        }

    }

The magic is all in the new DynamicAttribute class. This attribute is unnecessary for the assembly you compiled, but it is important for anyone referencing that assembly. The compiler will use that attribute to know that it has to treat the property, field, or method as though the dynamic keyword were used.

When I saw that, I imagined the possibilities. What if I make a class have static behavior in my assembly but dynamic behavior in a calling assembly? I set out to make this happen, but then I ran into a big roadblock:

Do not use 'System.Runtime.CompilerServices.DynamicAttribute'. Use the 'dynamic' keyword instead.

That's unfortunate, and I couldn't find a way around it. I see nothing being reflected back from the DynamicAttribute class, so the error must be baked into the compiler.

So, it appears that you can't use this class yourself. However, it is useful to know when reflecting a class that you can check for that attribute if you need to know if it is a dynamic type. Though, I do suspect an IsDynamic property will appear on the Type class sooner or later.

PDF From Web in AxAcroPDF

Chris Eargle — Wed, 03 Jun 2009 22:52:28 GMT

If you've ever needed to host a PDF in a windows form application, the easiest way to do so is by using the ActiveX control provided by Adobe Acrobat. Accessing it is easy: Right click the toolbox, select Choose Items, select COM Components, then check Adobe PDF Reader.

The Adobe PDF Reader control now shows up in your toolbox under the General tab. You can move this to a different tab by dragging and dropping.

If you drag this to your Windows Form, it now acts like a regular control. Its default name is axAcroPDF1.

The typical way to display a pdf in the control is by using the LoadFile method. Unfortunately this method does not work for loading from a url. Instead, there is property to set for that: src.

axAcroPDF1.src = url; 

However, you may have another reason for storing the pdf on the disk before displaying it. Here's the code that will help you in that situation. Note that WebClient is located in the System.Net namespace.

string fileName = Path.GetTempFileName();

WebClient client = new WebClient();

client.DownloadFile(url, fileName);

axAcroPDF1.LoadFile(fileName);

Edit Object in Properties Pane

Chris Eargle — Tue, 02 Jun 2009 00:05:40 GMT

When creating a designer for Visual Studio, you may want to allow editing in the properties pane. This took me a while to figure out how to do, because the terminology wasn't quite what I expected it to be. Here's how I accomplished this task.

The window pane that hosts the designer implements IVsWindowPane. This interface contains a method called SetSite, which will provide a pointer to an object that implements IServiceProvider. I instantiate a ServiceProvider and assign this to a ServiceProvider property on the editor.

public int SetSite(IOleServiceProvider psp)
{
decisionTableEditor.ServiceProvider = new ServiceProvider(psp);
return VSConstants.S_OK;
}

Inside the code for DecisionTableEditor, I have a private method called ShowProperties. This method will take a SelectionContainer that it will pass to the TrackSelection service. The service is obtained using the ServiceProvider's GetService method. The container is passed into the TrackSelection's OnSelectChange method. It is important to note that you can't change this to pass in the array of objects (either as an array or as params) and assign it to the selection containers SelectedObjects because it interrogates the the type of array in deciding what properties to show in the panel (which will be none for object).

private void ShowProperties(SelectionContainer container)

{

    var track = ServiceProvider.GetService(typeof(STrackSelection)) as ITrackSelection;

    if (track != null)

    {

        track.OnSelectChange(container);

    }

}

When you want to call ShowProperties, you create a SelectionContainer and set its SelectedObjects property to an array of the object you wish to show. If the properties window needs to be cleared, passing in null for the container will do the trick.

SelectionContainer selectionContainer = null;

if (ColumnIndex >= 0)

{

    selectionContainer = new SelectionContainer();

    selectionContainer.SelectedObjects = new[] { DecisionTable.Columns[ColumnIndex] };

}

ShowProperties(selectionContainer);

The next step is deciding what to show. By default, public properties will show up. If they're read-only, they will be read-only in the Properties pane. In the class definition for the objects you wish to show in the Properties pane, you can assign attributes to be more descriptive. These attributes are located in the System.ComponentModel namespace. The most important is probably the BrowsableAttribute, as it allows you to hide properties from the Properties pane. DescriptionAttribute and CategoryAttribute are useful as well, but you will need to deep dive System.ComponentModel if you want to get the full power of the Properties pane.

Visual Studio 2010 Beta 1 Available Today

Chris Eargle — Mon, 18 May 2009 14:35:28 GMT

Mike Ormond has announced that Visual Studio Beta 1 (including .NET Fx 4.0) will be available to MSDN subscribers later today.

He also posted a few screenshots. I admit that I'm somewhat saddened by the removal of the triangles.

GacUtil, MPF, and CSProj

Chris Eargle — Thu, 30 Apr 2009 16:13:03 GMT

Yesterday, I wrote about running GacUtil from within the AfterBuild target, due to some constraints with MPF and T4.

I discovered that the path I provided was wrong. It's the only GacUtil.exe under the Microsoft.NET folder, but it won't register the assembly. Since I wasn't sure which path I should be using, I used the GacUtil task from MSBuild Community Tasks. Here is the relevant code it uses to retrieve the path to gacutil.exe:

protected override string GenerateFullPathToTool()
{
return ToolLocationHelper.GetPathToDotNetFrameworkSdkFile(ToolName, TargetDotNetFrameworkVersion.Version20);
}
protected override string ToolName
{
get { return "gacutil.exe"; }
}

This was fine, but it turns out that you get an error from regpkg.exe if the assembly is location in the GAC if you're trying to generate from a path. 

regpkg : warning : The Assembly specified at [Path]\[Assembly]cannot be loaded because an alternate copy with the same identity exists in the Assembly probing path at 'C:\WINDOWS\assembly\GAC_MSIL\[Assembly]\1.0.0.0__7c2bf94927fd6e28\[Assembly]. The Assembly at 'C:\WINDOWS\assembly\GAC_MSIL\[Assembly]\1.0.0.0__7c2bf94927fd6e28\[Assembly] will be loaded instead.
regpkg : error : Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.
Could not load file or assembly '[Assembly], Version=1.0.0.0, Culture=neutral, PublicKeyToken=7c2bf94927fd6e28' or one of its dependencies. The system cannot find the file specified.

To fix this, I made the GacUtil uninstall the assembly in the BeforeBuild target. However, I kept receiving the same error. Generating a diagnostic log from MSBuild showed me the actual culprit: the RegisterManagedPackage target builds after the AfterBuild target. I fixed it by making AfterBuild depend on RegisterManagedPackage. I've pasted the final, relevant script below. Note that the RegPkg command in the AfterBuild is used to generate installer wix. TargetName is used in the GacUtil uninstall because it requires the name without the extension. 

<Import Project="$(MSBuildExtensionsPath)\MSBuildCommunityTasks\MSBuild.Community.Tasks.Targets" />
<Target Name="BeforeBuild">
   <GacUtil Command="Uninstall" Assemblies="$(TargetName)" ContinueOnError="true"/>
</Target>
<Target Name="AfterBuild" DependsOnTargets="RegisterManagedPackage">
  
   <RegPkg ItemToRegister="$(TargetPath)" ProductVersion="$(TargetVSVersion)" SDKVersion="$(VsSDKVersion)" OutputFile="..\Installer\RegistryEntries.wix" Unregister="false" UseCodeBase="false" UseRanu="false" />
   <GacUtil Assemblies="$(TargetPath)"/>
</Target>

GacUtil from Project File

Chris Eargle — Wed, 29 Apr 2009 22:51:09 GMT

Due to circumstances involving a MPF package and Text Templating (t4), I had to add an assembly to the GAC after compiling if I wanted to be able to run the generator in the VS Experimental. So, I added the following line to the AfterBuild target of the csproj file:

<Exec Command="gacutil /i $(TargetPath)"/>

Unfortunately, I received the following error when I compiled:

Error 155 The command "gacutil /i [PathToDll]" exited with code 9009. C:\Projects\AperioVisualStudioAddins\AperioVisualStudioAddins\AperioVisualStudioPackage.csproj 202 2 [DllName]

The problem is that when Visual Studio is building the project, it does not have access to the path. The way to make it work is to specify the fully qualified path and filename to gacutil.

<Exec Command="C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\gacutil.exe /i $(TargetPath)"/>

Team System 2010 Overview

Chris Eargle — Tue, 21 Apr 2009 14:32:55 GMT

Brian Harry has posted a list of features that will be in the upcoming beta 1 of Visual Studio 2010 Team System. Unfortunately, the date of release for beta 1 has not been announced yet.

Architecture (http://blogs.msdn.com/camerons/)

Architecture Explorer
Layer diagram
Use case designer
Activity designer
Component diagram
Logical class designer
Sequence diagram
Modeling project system
UML Model explorer
Architecture validation during build

Development & Database (http://blogs.msdn.com/habibh/)

Historical debugging
Test impact analysis
Improved code analysis
Improved profiling (especially multi-tier)
Database extensibility

Lab Management (http://blogs.msdn.com/amit_chatterjee, http://blogs.msdn.com/lab_management)

Multi-tier Environment creation and management
Automated deployment
Easily manage machine pools
Network fencing
Checkpoints

Test (http://blogs.msdn.com/amit_chatterjee, http://blogs.msdn.com/james_whittaker)

Test planning
Test case management
Test prioritization
Run management & reporting
Project quality reports
Manual test execution
Diagnostic recording (environment, video, etc)
UI Automation recording
Coded UI tests

TFS (my blog http://blogs.msdn.com/bharry)

Work item hierarchy & linking
Improved Agile template
MOSS & WSS Dashboards
Simplified reporting
Improved support for parallel development
Rollback
Build queuing and pooling
Gated checkin
Simplified setup
Scale out of web and data tiers
Admin console
Project move/archive/restore