Annotations for `__eq__`
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Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 30/100
- Issue type
- Documentation
- Clarity
- Needs clarification
- Activity status
- Stale
- Tech stack
- python
- Domain
- documentation
Research direction
Start by reading the typing specification and the linked discuss.python.org thread to understand the existing treatment of eq. The work is complete when the specification gives agreed guidance for non-overlapping comparisons, non-boolean returns, NotImplemented, and errors, with library authors able to apply it consistently.
Written by the indexing model from the issue text.
Description
It would be useful to have more guidance on how __eq__ methods should be annotated.
A few considerations:
- Enable type checkers to warn on non-overlapping equality comparisons. The type annotations should ideally allow type checkers to look at a check like
A() == B()and verify whether it can ever return True. - Some level of support for
__eq__returning a non-boolean (classic example: numpy arrays) - How to think about
__eq__methods that return NotImplemented on unrecognized types versus those that throw an error
See also https://discuss.python.org/t/make-type-hints-for-eq-of-primitives-less-strict/34240
Covering this in the typing spec is important because it affects how library authors should annotate __eq__ methods in their libraries if they want all type checkers to understand these methods.
- Dominant language
- Python
- Stars
- 1.8k
- Forks
- 302
- Avg merge
- 23h
- Merged PRs (30d)
- 8
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