How do you Define Function Type Hints in Python?

Defining Function Type Hints in Python

In Python, type hints provide a way to specify the expected data types of variables and function arguments and return values. While various types are available for hints, there's no explicit "Function" type. This article presents the solution to specifying function types effectively.

To specify a variable's type hint as a function type, use typing.Callable:

from typing import Callable

def my_function(func: Callable):
    pass

This indicates that the func parameter is expected to be a callable object, such as a function or method.

Note: Callable alone is equivalent to Callable[..., Any], which means it takes any number and type of arguments and returns a value of any type. For a more specific definition, specify the types of input arguments and return values:

def sum(a: int, b: int) -> int:
    return a + b

Callable[[int, int], int]

In general, the syntax for a function type hint is:

Callable[[ParamType1, ParamType2, ..., ParamTypeN], ReturnType]

Where ParamType1...ParamTypeN are the types of each parameter, and ReturnType is the expected return type.

The above is the detailed content of How do you Define Function Type Hints in Python?. For more information, please follow other related articles on the PHP Chinese website!