Moving compile items in msbuild into a separate file? - visual-studio

Question

This is probably a FAQ, but we weren't able to find a solution even after a lot of searching.
We have a number of msbuild files that all operate on the same set of source files. (It's not particularly relevant but they compile to completely different platforms.) To make managing these a little simpler, we'd like to move the <Compile> source file names to a separate file and reference that from all the msbuild files.
We tried cutting the <ItemGroup> containing the <Compile> items and pasting it into a new file, and surrounding it with
<Project DefaultTargets="Build" ToolsVersion="3.5" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
and then referencing that file from the original with
<Import Project="Common.files.csproj" />
but that does not work - the solution opens (with a warning since we hacked the default config), but no items appear in the Solution Explorer.
What are we doing wrong?

Answer 1

Tried with Visual Studio 2010:
1) Create your external .proj (or .target) file and add your files (I used a different item name but that shouldn't matter)
<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<ItemGroup>
<ExternalCompile Include="Program.cs" />
<ExternalCompile Include="Properties\AssemblyInfo.cs" />
</ItemGroup>
</Project>
2) Import your external .proj file at the top of your Visual Studio project file:
<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<Import Project="MyExternalSources.proj" />
<PropertyGroup>
...
and modify the Compile ItemGroup like this:
...
<ItemGroup>
<Compile Include="#(ExternalCompile)" />
</ItemGroup>
...
Warning: You'll have to add new items/files to your external .proj file - all items/files added from within Visual Studio will end up like this:
...
<ItemGroup>
<Compile Include="#(ExternalCompile)" />
<Compile Include="MyNewClass.cs" />
</ItemGroup>
...

Answer 2

I've never seen "include" files work with MSBuild. Obviously Targets files work this way, but I haven't seen a partial msbuild file included in another. COuld you use a method such as illustrated in this?
http://msdn.microsoft.com/en-us/library/ms171454(VS.80).aspx
Using wildcards is how I've addressed this in the past.