Nested files with 'DependentUpon' in Visual Studio

Here's a really neat trick discovered by my colleague Preet that you can use to show a relationship between files in Visual Studio, just like Microsoft does with partial 'designer' classes. You've probably noticed when you add a new windows form in VS 2005 that two files are created: MyForm.cs and MyForm.designer.cs. The designer file contains all the code that's generated by the form designer and the other file is where you write your user code. Preet showed me that you can do the same thing by modifying the .csproj file (aka the MSBuild file) and add a DependentUpon child element to any item that you want to appear below another. Here's a snippet of a .csproj that has three files, all partial classes of 'Foo'. In the solution explorer Foo.1.cs appears nested below Foo.cs and Foo.1.1.cs appears below Foo.1.cs.

  
  <ItemGroup>
    <Compile Include="Foo.1.1.cs">
      <DependentUpon>Foo.1.cs</DependentUpon>
    </Compile>
    <Compile Include="Foo.1.cs">
      <DependentUpon>Foo.cs</DependentUpon>
    </Compile>
    <Compile Include="Foo.cs" />
    <Compile Include="Program.cs" />
    <Compile Include="Properties\AssemblyInfo.cs" />
  </ItemGroup>

The only way of doing this at the moment is by editing the .csproj file, but it's pretty cool, especially if you're writing code generators and GAT tools like I have been recently where you might want generated content to be visually related to user written code.