python / python/typeshed

`abc.ABC.__slots__` should be marked with `ClassVar`

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Python
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Description

According to the python official documentation, slots are class variables. Therefore, in the class abc.ABC, the variable __slots__ should be annotated as ClassVar[Sequence[str]]. There is currently no annotation. It means that in all subclasses of abc.ABC, the variable __slots__ is considered as an instance variable.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the typeshed stub defining abc.ABC and inspect how slots is currently declared. Mark it as ClassVar[Sequence[str]], then verify that subclasses no longer treat slots as an instance variable using the repository's relevant type-checking tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
devtools
Issue type
Bug
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
55/100

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