New submission from Gregory Beauregard <g...@greg.red>:
Consider the following.
```
import logging
from typing import Annotated, Callable, ParamSpec, TypeVar
T = TypeVar("T")
P = ParamSpec("P")
def add_logging(f: Callable[P, T]) -> Callable[P, T]:
"""A type-safe decorator to add logging to a function."""
def inner(*args: Annotated[P.args, "meta"], **kwargs: P.kwargs) -> T:
logging.info(f"{f.__name__} was called")
return f(*args, **kwargs)
return inner
@add_logging
def add_two(x: float, y: float) -> float:
"""Add two numbers together."""
return x + y
```
This raises an error at runtime because P.args/P.kwargs cannot pass the
typing._type_check called by Annotated because they are not callable(). This
prevents being able to use Annotated on these type annotations.
This can be fixed by adding __call__ methods that raise to typing.ParamSpecArgs
and typing.ParamSpecKwargs to match other typeforms.
I can write this patch given agreement
----------
components: Library (Lib)
messages: 412546
nosy: AlexWaygood, GBeauregard, Jelle Zijlstra, gvanrossum, kj
priority: normal
severity: normal
status: open
title: typing.Annotated cannot wrap typing.ParamSpec args/kwargs
type: behavior
versions: Python 3.10, Python 3.11, Python 3.9
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue46643>
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