Why does the docs example for ParamSpec use collections.abc.Callable?

Documentation
1

I am so happy that it’s possible to type decorators nicely now. But I noticed the docs for ParamSpec give this example:

from collections.abc import Callable
from typing import TypeVar, ParamSpec
import logging

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: P.args, **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

And it made me wonder… is there a reason that from collections.abc import Callable is used instead of from typing import Callable?

Is the latter deprecated now?

2

According to the Python documentation typing.Callable is deprecated since Python 3.9 due to the PEP 585 – Type Hinting Generics In Standard Collections. In resume the PEP proposes to allow Generics in the standard collections[1] to remove the need to maintain a parallel type hierarchy in the typing module [2].

Although is indeed odd the documentation mentioning the change in the deprecated “typing.Callable”.

2 Likes
3

Good to know - it is totally deliberate :slight_smile:

and I guess it makes sense that the typing.Callable docs are where it says that it’s deprecated