Title: `inspect.is*function()` overloads do not match the runtime behavior · Issue #15293 · python/typeshed · GitHub
Open Graph Title: `inspect.is*function()` overloads do not match the runtime behavior · Issue #15293 · python/typeshed
X Title: `inspect.is*function()` overloads do not match the runtime behavior · Issue #15293 · python/typeshed
Description: TypeGuard-based overloads for inspect.is*function() were added in #8057, but they are somewhat controversial. First, the first overload defines the return type via collections.abc.
Open Graph Description: TypeGuard-based overloads for inspect.is*function() were added in #8057, but they are somewhat controversial. First, the first overload defines the return type via collections.abc.
X Description: TypeGuard-based overloads for inspect.is*function() were added in #8057, but they are somewhat controversial. First, the first overload defines the return type via collections.abc.<Object>, w...
Opengraph URL: https://github.com/python/typeshed/issues/15293
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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"`inspect.is*function()` overloads do not match the runtime behavior","articleBody":"[`TypeGuard`](https://docs.python.org/3/library/typing.html#typing.TypeGuard)-based overloads for `inspect.is*function()` were added in #8057, but they are somewhat controversial.\n\nFirst, the first overload defines the return type via `collections.abc.\u003cObject\u003e`, while the rest define it via `types.\u003cObject\u003eType`. As a result, type checkers infer the narrower type when the known return type differs from `collections.abc.\u003cObject\u003e`:\n\n```python\nfrom collections.abc import Coroutine\nfrom inspect import iscoroutinefunction\nfrom types import CoroutineType\nfrom typing import reveal_type\n\ndef native_coroutine_factory() -\u003e CoroutineType[None, None, None]: ...\ndef coroutine_factory() -\u003e Coroutine[None, None, None]: ...\ndef object_factory() -\u003e object: ...\n\nif iscoroutinefunction(native_coroutine_factory):\n reveal_type(native_coroutine_factory)\n # () -\u003e CoroutineType[None, None, None]\n\nif iscoroutinefunction(coroutine_factory):\n reveal_type(coroutine_factory)\n # () -\u003e Coroutine[None, None, None]\n\nif iscoroutinefunction(object_factory):\n reveal_type(object_factory)\n # () -\u003e CoroutineType[Any, Any, Any]\n```\n\nSecond, `inspect.is*function()` also returns `True` for functions that return a non-native object (for example, if the function was compiled via Cython), which means that the return type may not be `types.\u003cObject\u003eType`:\n\n```python\n#!/usr/bin/env python3\n\nimport inspect\n\n\ndef generator_function():\n yield\n\n\nasync def coroutine_function():\n pass\n\n\nasync def async_generator_function():\n yield\n\n\ndef main():\n # `True` on both CPython and Cython:\n print(inspect.isgeneratorfunction(generator_function))\n print(inspect.iscoroutinefunction(coroutine_function))\n print(inspect.isasyncgenfunction(async_generator_function))\n\n # `True` on CPython, `False` on Cython:\n print(inspect.isgenerator(generator_function()))\n print(inspect.iscoroutine(coro := coroutine_function()))\n print(inspect.isasyncgen(async_generator_function()))\n\n coro.close() # to avoid `RuntimeWarning`\n\nif __name__ == \"__main__\":\n main()\n```\n\nThird, I am also concerned about [the Python core developer's statement](https://github.com/python/cpython/issues/143908#issuecomment-3761121758) that [`iscoroutinefunction()`](https://docs.python.org/3/library/inspect.html#inspect.iscoroutinefunction) is basically defined for callable objects that return awaitable objects. Does this mean that we should use [`Awaitable`](https://docs.python.org/3/library/collections.abc.html#collections.abc.Awaitable) as the return type instead of [`Coroutine`](https://docs.python.org/3/library/collections.abc.html#collections.abc.Coroutine) for [`inspect.iscoroutinefunction()`](https://docs.python.org/3/library/inspect.html#inspect.iscoroutinefunction) (since if users follow that definition, [`inspect.markcoroutinefunction()`](https://docs.python.org/3/library/inspect.html#inspect.markcoroutinefunction) will be applied just as broadly, even though this somewhat contradicts the documentation)?","author":{"url":"https://github.com/x42005e1f","@type":"Person","name":"x42005e1f"},"datePublished":"2026-01-16T19:07:29.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/15293/typeshed/issues/15293"}| route-pattern | /_view_fragments/issues/show/:user_id/:repository/:id/issue_layout(.:format) |
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