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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Bound instance methods fail to satisfy `runtime_checkable` `Protocol`","articleBody":"# Bug report\n\n### Bug description:\n\n#103034 added some protections around `isinstance` checks of `runtime_checkable` `Protocols` using `inspect.getattr_static`. This [uses](https://github.com/python/cpython/blob/37c57dfad12744608091653fd753a1f770e2479b/Lib/inspect.py#L1733) `inspect._check_instance` which [uses](https://github.com/python/cpython/blob/main/Lib/inspect.py#L1669)  `object.__getattribute__(obj, \"__dict__\")`, which fails for bound instance methods (although `obj.__dict__` does work), so they cannot fulfill `runtime_checkable` `Protocols` anymore.\n\n```\nfrom typing import Protocol, runtime_checkable\n\n\n@runtime_checkable\nclass Labelled(Protocol):\n    label: str\n\n\nclass A:\n    def f(self):\n        pass\n\n\nA.f.label = \"f\"\n\na = A()\nprint(a.f.__dict__)  # {'label': 'f'}\nprint(object.__getattribute__(a.f, \"__dict__\"))  # AttributeError\n\nassert isinstance(a.f, Labelled)  # AssertionError\n```\n\nIs this an intended/known change? Could it be noted in the changelog [here](https://docs.python.org/3/whatsnew/3.12.html#typing) as an example of case that will no longer work?\n\n---\n\nCreated from https://github.com/python/cpython/pull/103034#issuecomment-2488670252\ncc @AlexWaygood \n\n### CPython versions tested on:\n\n3.12\n\n### Operating systems tested on:\n\nLinux","author":{"url":"https://github.com/GDYendell","@type":"Person","name":"GDYendell"},"datePublished":"2024-11-20T14:32:36.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/127059/cpython/issues/127059"}