python / python/typing

Type checking for `property.{fget,fset,fdel}`

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topic: other
Dominant language
Python
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Description

When trying to fix an issue in typeshed we found that both mypy and pyright raised incorrect errors that were also inconsistent with one another so I'm creating this issue to facilitate further discussion on resolving this.

class A:
    @property
    def foo(self):
        return 'a'

A.foo.fget(A())

mypy: "Callable[[A], Any]" has no attribute "fget"
pyright: Expected 0 positional arguments

Initial PR attempt and relevant discussions can be found here

Contributor guide

No contributing guide indexed for this repository

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

Review the linked typeshed issue #7516 and PR #7520 first, then compare the mypy and pyright diagnostics for the example in this issue. A useful outcome is an agreed interpretation of property.fget, property.fset, and property.fdel, followed by a concrete, validated follow-up change.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
devtools
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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