Add a Sphinx extension to document cached properties of slots classes

[clayote]

Summary

This is a small extension for Sphinx, the documentation generator that attrs uses. Where cached properties on slots classes were missing previously (#1325), this extension restores them.

I added a dictionary to slotted class objects, __attrs_cached_properties__, where they keep the cached property objects for Sphinx.

I wrapped the __slots__ tuple itself in a custom collections.abc.Sequence that acts exactly like its tuple, but isn't considered one for the purposes of isinstance(), because, currently, I have to do that in order to make Sphinx use the extension on slots. I have a PR for Sphinx open to make that unnecessary.

To use the extension, add "attrs.sphinx_cached_property" to extensions in your Sphinx conf.py.

Pull Request Check List

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• Added tests for changed code.
  Our CI fails if coverage is not 100%.
• Changes or additions to public APIs are reflected in our type stubs (files ending in .pyi).
  • ...and used in the stub test file typing-examples/baseline.py or, if necessary, typing-examples/mypy.py.
  • If they've been added to attr/__init__.pyi, they've also been re-imported in attrs/__init__.pyi.
• Updated documentation for changed code.
  • New functions/classes have to be added to docs/api.rst by hand.
  • Changes to the signatures of @attr.s() and @attrs.define() have to be added by hand too.
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    The next version is the second number in the current release + 1.
    The first number represents the current year.
    So if the current version on PyPI is 22.2.0, the next version is gonna be 22.3.0.
    If the next version is the first in the new year, it'll be 23.1.0.
    • If something changed that affects both attrs.define() and attr.s(), you have to add version directives to both.
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• Changes (and possible deprecations) have news fragments in changelog.d.
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[clayote]

I wrote a test for this, but it won't run in CI currently, because that test requires Sphinx to be installed. That's why the pre-commit check is failing.

[clayote]

I need to make sure the :members: directive works, too...

[clayote]

I haven't a clue what's going on with those interrogate failures! It seems to be related to coverage somehow? @hynek ?

[hynek]

I haven't a clue what's going on with those interrogate failures! It seems to be related to coverage somehow? @hynek ?

on a quick look I see two tests without docstrings

[clayote]

Checks are passing, I think it's ready @hynek

[clayote]

Looks like a misconfigured test to me

[sscherfke]

@clayote Your actions create a lot of noise and many notifications. It would be helpful if you did more work offline and and only post updates and questions when really needed. This would make it easier for reviewers/maintainers to help you.

[AdrianSosic]

@clayote: feel free to ping me when it's ready for me to test 👌🏼

[clayote]

@AdrianSosic Please do

[clayote]

Huh, I guess I'd better write documentation for the extension.

It's not part of the API, really? Where should it go...