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Summary

The type hinting for the or_ function presumes that all validators used have the same input type though that is not a requirement. This adds several overloads and a fall-through Any type catch-all to the or_ function that will help satisfy the type check.

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@ProfDoof ProfDoof changed the title Improve type hinting of instance_of and or_ Improve type hinting of or_ Sep 12, 2025
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I believe that I need to add some mypy tests to adequately verify that or_ works the way that I believe it does. However, it's unclear where I should add that.

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hynek commented Sep 21, 2025

I believe that I need to add some mypy tests to adequately verify that or_ works the way that I believe it does. However, it's unclear where I should add that.

That would go to tests/typing_example.py – just exercise the types (it doesn't have to be runnable) – thanks!

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hynek commented Sep 28, 2025

So I can't make this fail on Mypy… maybe its plugin somehow works around this? Have you had any failures somehow somewhere?

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hynek commented Sep 28, 2025

OK, this fails on Pyright:

@attrs.define
class ValidatedInconsistenOr:
    num: int = attrs.field(
        validator=attrs.validators.or_(
            # Various types of validators.
            attrs.validators.ge(0),
            attrs.validators.instance_of(object),
        )
    )

I'll split up the type hints a bit.

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Thanks!

@hynek hynek added this pull request to the merge queue Sep 28, 2025
Merged via the queue into python-attrs:main with commit f8f7a2e Sep 28, 2025
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2 participants