Declare input parameters for function-type in parameter declaration using typing [duplicate]

Question

Context

Assume a function taking in a function like this:

def some_func(
        parameter_1: str
        , func: function
    ):
    pass

As can be seen func shall be a function passed to some_func.

Anyhow, func shall be a function taking in a specifc parameter-type:

def func(
        specific_parameter_of_type_string: str
    ):
    pass

Question

How do I declare in some_func() that the parameter func shall be a function which takes in a str?

I looked into the typing-module but did not find the solution to my question. Anyhow, I think it should be solvable with it...

The result would resemble something like this I assume:

import typing

def some_func(
        parameter_1: str
        , func: typing.Function[str] # Example! This does not exist in typing
    ):
    pass

@not_speshal: Sorry, but this is not a solution to this problem - Casting is something entirely different than type hinting. — Markus
– Markus, Commented Feb 15, 2022 at 18:08
"func shall be a function taking in a specifc parameter-type" — not_speshal
– not_speshal, Commented Feb 15, 2022 at 18:10
@not_speshal: Yes exactly, and this is not declared by casting but by typing :) — Markus
– Markus, Commented Feb 15, 2022 at 18:16
@MisterMiyagi: Yes I was :) Encountered this also in the moment you wrote :D — Markus
– Markus, Commented Feb 15, 2022 at 18:17

Markus · Accepted Answer · 2022-02-15 18:15:31Z

0

Reading the typing documentation more carefully I encountered that functions are actually referred to as typing.Callables as can be read here.

Thus, this can be used to specify both, the return type and input arguments:

Callable[[Arg1Type, Arg2Type], ReturnType]

The solution is then:

import typing

def some_func(
        parameter_1: str
        , func: typing.Callable[[str], None]
    ):
    pass

answered Feb 15, 2022 at 18:15

Markus

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