How to define the size of a tuple or a list in the type hints

Question

Is there a way to define the size of a tuple or list in the type hints of arguments?

At the moment I am using something like this:

    from typing import List, Optional, Tuple

    def function_name(self, list1: List[Class1]):
        if len(list1) != 4:
            raise SomeError()
        pass
        # some code here

I am searching for a leaner way to do this.

Answer 1

For lists it make no sense because they are dynamic, for tuples on the other hand the number of types inside the definition is the number of elements it holds:

from typing import Tuple

example_1: Tuple[int, int] = (1, 2)  # This is valid
example_2: Tuple[int, int] = (1, 2, 3)  # This is invalid
example_3: Tuple[int, ...] = (1, 2, 3, 4)  # This is valid, the ellipses means any number if ints
example_4: Tuple[int, ...] = (1, 'string')  # This is invalid

# So in your case if you need 4 you can do something like this
My4Tuple = Tuple[Class1, Class1, Class1, Class1]
def my_function(self, arg1: My4Tuple):
    pass

Always remember that this is not enforced at runtime