function becomes non-iterable when using a global variable inside it

Question

beginner here, im interested in solving the problem but also learning the 'how' and 'why' of it

so i have this function:

import random

move = 0

def computer_move():
    global move
    if move == 0:
        while True:
            rand = random.randrange(0, 9)
            if positions[rand].state:
                move = 1
                positions[rand].state = False
                positions[rand].played = 'circle'
                return positions[rand].x,positions[rand].y

before i had the 'move' variable declared outside the function everything worked fine except whenever the function is called the variable reset to 0, so i had to declare it outside and naturally i had to use it with global. except now when i call the function like so:

x, y = computer_move()

i get TypeError: cannot unpack non-iterable NoneType object on the line of the function call

i tired a few ideas but nothing seems to work. Appreciate any help or clarification

Answer 1

In Python, a function returns None if no return is executed. Your function may return None like this if move != 0. In such a case, x, y = computer_move() will be equivalent to x, y = None, which is causing the TypeError.