How can I repeat a def function in Canvas?

Question

I want this def function to repeat itself as soon as the ball hits the ground (border of the window) I tried using if , for loop and while: , but I wasn't able to make it work. I'm a beginner so maybe I'm just making stupid mistakes. Thanks for the help.

import tkinter
canvas = tkinter.Canvas(width=600, height=600)
canvas.pack()

def ball():
    canvas.delete('all')
    global y
    canvas.create_oval(x - 5,y - 5,x + 5,y + 5, fill = 'red')
    y = y + 2
    if y < 600:
        canvas.after(2, ball)
y = 0
x=300
ball()

TL;DR : I want to repeat a def function in Python after a certain event.

Answer 1

I implement a situation with python to show you how you can use the while loop and also using return for your functions to exit the loop after some event. It's just an example for better understanding the answer. And do not use global variables in your code. It's just for the example.

a = 100

def count_down():
  global a
  a -= 1
  if a > 0:
    return True
  return False


in_the_loop = True

while(in_the_loop):
  in_the_loop = count_down()
  print(a)

Maybe this snippet will give some idea about your case to how to exit from the base function by simply adding return to that.

Answer 2

It sounds like you just want to reset the y value:

import tkinter
canvas = tkinter.Canvas(width=600, height=600)
canvas.pack()

def ball():
    canvas.delete('all')
    global y
    canvas.create_oval(x - 5,y - 5,x + 5,y + 5, fill = 'red')
    y = y + 2
    if y >= 600:
        y = 0   # Restart y from 0 again
    canvas.after(2, ball)
y = 0
x=300
ball()