Exploring the Code for the New .NET 3.5 Classes

I often use the free and awesome decompiler Reflector to peer into the source code of Microsoft's .NET Framework. It's an indispensable tool. However, I had a little difficulty viewing the underlying source code for some of the new .NET 3.5 classes. In particular, for a recent article I was interested in looking at what was happening underneath the covers when the DataPager control was rendered. The DataPager is a new control in ASP.NET 3.5 used to render a paging interface for the ListView control (also new to 3.5).

By default, Reflector had the v2.0 assemblies loaded. “No problem,” I thought, “I'll just navigate to the 3.5 assemblies in the %WINDIR%\Microsoft.NET\Framework folder and open the System.Web assemby from there. While there is a 3.5 subfolder there, it only includes a sprinkling of assemblies, and none of the 3.5 assemblies I was interested in. The .NET 3.5-specific classes are installed in the GAC in the System.Web.Extensions.dll assembly. Reflector, it appears, can't locate this assembly and I couldn't reach it through Windows Explorer.

I was able to use Reflector to dig into this assembly, but I'm sure there's an easier way to do it. I'm going to share my approach, but I invite anyone who knows of a simpler technique to post instructions in the comments. One possible solution would be to update Visual Studio 2008 so that the .NET Framework code can be stepped into during debugging. I tried applying the hotfix a while back and got an error, and have not yet taken the time to investigate the error further. With the .NET Framework source code integration can you view the source code through VS 2008 like with Reflector, or is the code only accessible when debugging?

To open the System.Web.Extensions.dllfrom Reflector, perform the following steps:

• Drop to the command line (Start / Run / cmd.exe)
• Navigate to the appropriate GAC folder, %WINDIR%\assembly\GAC_MSIL\System.Web.Extensions\3.5.0.0__31bf3856ad364e35\
• Copy the System.Web.Extensions.dll to another location on my hard drive (such as C:\MyAssemblies\).
• Once the assembly is “freed” from the GAC, you can open it in Reflector as you would any assembly

Hope this helps!

UPDATE FROM JAMES NEWTON-KING: “You can access the 3.0 and 3.5 assemblies at C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5” (That sure simplifies things!)