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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Allow non-descriptor callables in `functools.singledispatchmethod`","articleBody":"# Bug report\n\n### Bug description:\n\nWhen a non-descriptor callable (such as a lambda or a class instance) is registered as a handler, `singledispatchmethod` unconditionally attempts to call the `__get__` method on that handler during dispatch.\nThis results in an AttributeError, because non-descriptor callables do not have a __get__ method.\nThis behavior directly violates the explicit guarantee in `singledispatchmethod`'s own [docstring](https://github.com/python/cpython/blob/main/Lib/functools.py#L1014), which states that it does handle non-descriptor callables.\n\n```python\nimport functools\n\nclass MyCallable:\n    def __call__(self, host_self, arg):\n        return f\"Handled {arg} via MyCallable\"\n\nclass Host:\n    @functools.singledispatchmethod\n    def my_method(self, arg):\n        return f\"Base handling for {arg}\"\n\ncallable_instance = MyCallable()\nHost.my_method.register(int, callable_instance)\n\n\nh = Host()\n\nh.my_method(123)\n```\n\n```python\nAttributeError: 'MyCallable' object has no attribute '__get__'. Did you mean: '__ge__'?\n```\n\n\n### CPython versions tested on:\n\n3.12\n\n### Operating systems tested on:\n\nLinux\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-140884\n* gh-141523\n* gh-141710\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/T90REAL","@type":"Person","name":"T90REAL"},"datePublished":"2025-11-01T04:24:04.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/140873/cpython/issues/140873"}