103 – Typing *args and **kwargs

When typing functions with an arbitrary number of positional arguments (*args) or with an arbitrary number of keyword arguments (**kwargs), the type hints should target the values that you’ll accept. In other words, don’t add type hints for the tuple args as a whole or for the dictionary kwargs as a whole.

The signature below denotes a function my_max that accepts a variable number of integers and a variable number of keyword arguments that are Booleans:

def my_max(
    *args: int,
    **kwargs: bool,
) -> int:
    ...

On the other hand, the signature below denotes a function my_max that accepts a variable number of tuples of integers and a variable number of keyword arguments that are dictionaries that map strings to Booleans:

def my_max(
    *args: tuple[int, ...],
    **kwargs: dict[str, bool],
) -> int:
    ...