Add typing support to get_solo

[Viicos]

As get_solo hits the cache, type checkers can't infer the return type of the method correctly. User could use typing.cast or similar but having it fixed in the library directly sounds easier. typing.TypeVar is used as a workaround until typing.Self can be used without making use of typing_extensions.

[Viicos]

If you'd like to, we could add basic typing to the other parts of the library as well

[johnthagen]

I could see value in adding typing to this library, and enabling mypy checking of the project as a new CI check.

An example you could look at is:

• https://github.com/johnthagen/cppcheck-junit/blob/master/tox.ini#L32

Please configure Mypy in strict mode in pyproject.toml like:

[tool.mypy]
ignore_missing_imports = true
strict = true

We'll also want to add a py.typed file to the solo package and include it in MANIFEST.in.

[Viicos]

Great to hear you want to head into this direction. I added types to the whole library, and also updated some old compatibility code. Let me know if any changes are needed. As another PR, I think it would be great to have:

• black + isort/ruff
• Use PEP 517/518 for packaging

I you agree with this, I can make separate PRs

[johnthagen]

Great to hear you want to head into this direction. I added types to the whole library, and also updated some old compatibility code. Let me know if any changes are needed. As another PR, I think it would be great to have:

• black + isort/ruff
• Use PEP 517/518 for packaging

I you agree with this, I can make separate PRs

Let's make separate PRs for these things.

I'd prefer using Ruff for everything on the first bullet: formatting, linting and isort rules. You can see my example repo here for how I usually configure Ruff:

• https://github.com/johnthagen/python-blueprint?tab=readme-ov-file#code-style-checking
• https://github.com/johnthagen/python-blueprint/blob/main/pyproject.toml#L77

We may need to modify some of these rules for django-solo (e.g. we should keep the first diff a bit minimal rather than enabling too many of those rules).

[johnthagen]

I presume you are using django-solo in a production application. Could you test your application with this PR to smoke test that everything here works well for you at runtime?

Would also be great if you could double check that Mypy now type checks your usage of django-solo properly when installed from this PR.

[Viicos]

I presume you are using django-solo in a production application. Could you test your application with this PR to smoke test that everything here works well for you at runtime?

We are making use of django-solo extensively on an open source project, so I can try it there, I'll let you know tomorrow how it goes

[Viicos]

Here is a pull request making use of my branch:

• (Test PR) Update to typed django-solo open-formulieren/open-forms#3776

I had to add back get_cache as we were making use of it in a 3rd party library (I've also added a deprecation warning).

Regarding mypy, we don't run it yet, but I can already see from my IDE (which uses pyright) that .get_solo is correctly typed. Apart from that, tests are passing

[johnthagen]

Could you add a changelog entry for deprecating get_cache?

[Viicos]

Could you add a changelog entry for deprecating get_cache?

See c279dc4

[Viicos]

Looking at the remaining type issue, might be another mypy bug..

[Viicos]

This is a mypy bug (works with pyright), but I can't produce a MRE: playground. Maybe this only happens when split into multiple files

[johnthagen]

Thanks for the contribution, @Viicos!