New submission from David Caro <cascaran...@gmail.com>:
In version 3.2, bpo-8814 introduced copying the __annotations__ property from
the wrapped function to the wrapper by default.
That would be the desired behavior when your wrapper function has the same
signature than the function it wraps, but in some cases (for example, with the
contextlib.asynccontextmanager function) the return value is different, and
then the __annotations__ property will have invalid information:
In [2]: from contextlib import asynccontextmanager
In [3]: @asynccontextmanager
...: async def mytest() -> int:
...: return 1
...:
In [4]: mytest.__annotations__
Out[4]: {'return': int}
I propose changing the behavior of wraps, to only assign the __annotations__ by
default if there's no __annotations__ already in the wrapper function, that
would fit most default cases, but would allow to preserve the __annotations__
of the wrapper function when the types are explicitly specified, allowing now
to change the contextlib.asynccontextmanager function with the proper types
(returning now an AsyncContextManager) and keep the __annotation__ valid.
I'll try to get a POC and attach to the issue, but please comment with your
ideas too.
----------
components: Library (Lib)
messages: 373233
nosy: David Caro
priority: normal
severity: normal
status: open
title: Type annotations lost when using wraps by default
type: behavior
versions: Python 3.10, Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python
3.9
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue41231>
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