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.net-coremsbuildnugetpreprocessor

Define C# preprocessor symbol in NuGet package

Can a NuGet package define a preprocessor symbol for the consuming project? And if so, how?

Solution

  • If your package (My.ExamplePackage) contains an MSBuild file named like the package name + .targets in the build directory (so build\MyExamplePackage.targets), you can use it to amend the DefineConstants property that may have been set to defaults or reset in the project:

    <Project>
  <PropertyGroup>
    <DefineConstants>$(DefineConstants);MY_PREPOCESSOR_SYMBOL</DefineConstants>
  </PropertyGroup>
</Project>

    While the package can contain both a .props and .targets file, the .targets file will be imported after the main body of the csproj file being built so if it the project re-sets DefineConstants (meaning not adding to it by prepending $(DefineConstant);), the .targtes file has a chance of adding to this property.