How annotate a function that takes another function as parameter?

user_6178507 0
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I'm experimenting with type annotations in Python. Most cases are pretty clear, except for those functions that take another function as parameter.

Consider the following example:

from __future__ import annotations

def func_a(p:int) -> int:
    return p*5
    
def func_b(func) -> int: # How annotate this?
    return func(3)
    
if __name__ == "__main__":
    print(func_b(func_a))

The output simply prints 15.

How should I annotate the func parameter in func_b( )?

annotations python-3.x python
2 Answers

You can use the typing module for Callable annotations.

The Callable annotation is supplied a list of argument types and a return type:

from typing import Callable

def func_b(func: Callable[[int], int]) -> int:
    return func(3)
user_19538000

Shouldn't it just be function?

>>> type(func_a)
function
user_1417890
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