naming a configuration property function - msbuild

Question

I have a project that has a set of project contexts (full property groups omitted for brevity):
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'v82_Release|x64' ">
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'v90_Release|x64' ">
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'v90_Debug|x64' ">
The referenced assemblies vary by the version number at the beginning of the configuration
variable, so I opened the VS-generated csproj file and edited the references (parent Reference items omitted for brevity):
<HintPath>Lib\$(Configuration.Substring(0,3))\Assembly1.dll</HintPath>
<HintPath>Lib\$(Configuration.Substring(0,3))\Assembly2.dll</HintPath>
<HintPath>Lib\$(Configuration.Substring(0,3))\Assembly3.dll</HintPath>
This works, but is there a way to effectively define $(LibVersionNum) = $(Configuration.Substring(0,3)) and thus clean up my syntax?

Answer 1

Try this:
<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<PropertyGroup>
<Configuration>v82_Release</Configuration>
<Platform>x64</Platform>
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'v82_Release|x64' ">
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'v90_Release|x64' ">
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'v90_Debug|x64' ">
</PropertyGroup>
<PropertyGroup>
<LibVersionNum>$(Configuration.Substring(0,3))</LibVersionNum>
</PropertyGroup>
<ItemGroup>
<MyItem Include="Ref1">
<HintPath>Lib\$(LibVersionNum)\Assembly1.dll</HintPath>
</MyItem>
<MyItem Include="Ref2">
<HintPath>Lib\$(LibVersionNum)\Assembly2.dll</HintPath>
</MyItem>
<MyItem Include="Ref3">
<HintPath>Lib\$(LibVersionNum)\Assembly3.dll</HintPath>
</MyItem>
</ItemGroup>
<Target Name="Build">
<Message Text="Current Config: $(Configuration)"/>
<Message Text="%(MyItem.Identity): %(MyItem.HintPath)"/>
</Target>
</Project>