How to add a command line code generator to Visual Studio?

Question

I'm working on a project that uses code generation to generate C# classes using a command line tool from a text-based description. We are going to start using these descriptions for javascript too.

Currently these classes are generated and then checked in, however, I would like to be able to make the code generate automatically so that any changes are propagated to both builds.

The step that is run manually is:

servicegen.exe -i:MyService.txt -o:MyService.cs

When I build I want MSBuild/VS to first generate the CS file then compile it. It is possible to do this using, by modifying the csproj, perhaps using a MSBuild Task with Exec, DependentUpon & AutoGen?

Answer 1

Normally I would recommend a pre-build command be placed in a pre-build event, but since your command line tool will be creating C# classes needed for compiling, this should be done in the BeforeBuild target in the .csproj file. The reason for this is because MSBuild looks for the files it needs to compile between the time BeforeBuild is called and the time when PreBuildEvent is called in the overall process (you can see this flow in the Microsoft.Common.targets file used by MSBuild).

Call the Exec task from within the BeforeBuild target to generate the files:

<Target Name="BeforeBuild">
  <Exec Command="servicegen.exe -i:MyService.txt -o:MyService.cs" />
</Target>

See the Exec task MSDN documentation for more details about specifying different options for the Exec task.