Typing annotations and typechecking with mypy or pyright?

[moy]

We already have basic static analysis with flake8 (and the underlying pyflakes), but using typing annotations and a static typechecker may 1) find more bugs, 2) help our users by providing completion and other smart features in their IDE.

mypy is the historical typechecker, pyright is a more recent one which in my (very limited) experience works better (it's also the tool behind the new Python mode of VSCode). So I'd suggest pyright if we don't have arguments to choose mypy.

For now, neither tool can typecheck the project without error, so a first step would be to add the necessary annotations to get an error-free pyright check.

[hemberger]

Great suggestion! I'm 100% on board with adding type annotations. I'll let this sit for a while in case anyone wants to use this as a way to get involved with MechanicalSoup, but if there are no takers for a while (a month? a year?) then I'd be happy to add them myself.

[gophra]

I want to get involved with this issue. What I should do?

[hemberger]

@gophra Thanks for offering to get involved! As far as I understand, type annotations can be added incrementally, so I think getting some infrastructure for testing the type annotations would be important. I see a lot of unofficial GitHub Actions for both pyright and mypy, so it'd be really useful to get something like that set up.

Alternatively, if you aren't comfortable working with GitHub Actions, starting to typehint a few functions would still be a great start. How you contribute is totally up to you!