Julia: copy src files by ericphanson · Pull Request #3497 · pre-commit/pre-commit

This does feel a bit weird, I agree. The case here is when the precommit hook lives in a package, like JuliaTesting/ExplicitImports.jl#128. The existing hook support copies the Project/Manifest from the directory the hook lives in and tries to install the dependencies. But if the Project corresponds to a package, it (a) refuses to use Pkg to install that package as a dep (since the project name/uuid matches) and (b) fails as it lacks the src code.

An alternative way to use hooks that does work is to create a separate repo for the hook (outside the package) and use a Project.toml there to specify the package so it can be installed. This is done for example here: https://github.com/fredrikekre/runic-pre-commit. However I think it’s pretty inconvenient to maintain a second repo just for precommit support. Precommit is not a main way people use ExplicitImports for example, and it’s easy enough to add a hook file, but it’s a bit more to need to update/maintain a Project in a secondary repo.

The reason copying src feels ok in the scenario to me is that with the current setup is that we copy the Project.toml and when that is for a package, it needs the src code to run. So it is an expansion of the existing Project support.

Either way, we definitely do not need PythonCall. We already install deps. The question is just how to do it when the hook lives in the package itself.