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by Jiří {x2} Činčura

Targeting more frameworks with on csproj

12 Jun 2014 .NET, Visual Studio

I don’t like doing things twice or more times. And creating builds with csproj for multiple frameworks (like .NET 2.0, .NET 3.5, .NET 4.0, .NET 4.5) isn’t easy. Bunch of projects I’m following has like Project_40.csproj, Project_45.csproj and so on. That means you have to maintain two project files when you add, move or remove files.

Because I don’t like managing multiple project files, when I first started building FirebirdClient for multiple frameworks I simply switched target framework in Visual Studio, switched configuration and did the build. Not exactly a best scenario and actually few times I forgot to do the switch and produced wrong build. I had to double check what I was publishing.

But the csproj file is much more than what Visual Studio can set up. And it’s pretty easy to have everything under some condition - as I found when trying to juggle references to Entity Framework assemblies. Given the target framework is part of the project file it was just a question of changing the project file manually and see how Visual Studio will handle it and whether the Batch Build feature will be able to handle it. Long story short. It works (Visual Studio 2013 and tools (MSBuild, …) comming with Visual Studio 2013). The Batch Build has no problem with it. Visual Studio’s IntelliSense is sometimes confused when you switch target framework this way, but that’s not a big deal. Restarting Visual Studio solves it immediately, sometimes it solves itself after a while.

So how it’s done. The target framework is specified in TargetFrameworkVersion element and optionally there’s TargetFrameworkProfile in case there’s some profile (like .NET 4.0 Client). You wrap these into PropertyGroup matching your configuration and you’re done. Below is a sample comfiguration building under Release_40 for .NET 4.0 Client and Release_45 for .NET 4.5.

<PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release_40|AnyCPU'">
	<OutputPath>bin\Release_40\</OutputPath>
	<DefineConstants>TRACE;NET_40</DefineConstants>
	<Optimize>true</Optimize>
	<DebugType>pdbonly</DebugType>
	<PlatformTarget>AnyCPU</PlatformTarget>
	<ErrorReport>prompt</ErrorReport>
	<CodeAnalysisRuleSet>AllRules.ruleset</CodeAnalysisRuleSet>
	<Prefer32Bit>false</Prefer32Bit>
	<TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
	<TargetFrameworkProfile>Client</TargetFrameworkProfile>
</PropertyGroup>
<PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release_45|AnyCPU'">
	<OutputPath>bin\Release_45\</OutputPath>
	<DefineConstants>TRACE;NET_45</DefineConstants>
	<Optimize>true</Optimize>
	<DebugType>pdbonly</DebugType>
	<PlatformTarget>AnyCPU</PlatformTarget>
	<ErrorReport>prompt</ErrorReport>
	<CodeAnalysisRuleSet>AllRules.ruleset</CodeAnalysisRuleSet>
	<Prefer32Bit>false</Prefer32Bit>
	<TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
	<TargetFrameworkProfile>
	</TargetFrameworkProfile>
</PropertyGroup>

When I’m not sure what should go into TargetFrameworkVersion and TargetFrameworkProfile I just copy the values from fresh project. 😉

Obvious trick. Hope it helps you to lower the amount of “manual labor” you need to do when targeting multiple frameworks.