Python Turtle becomes unresponsive and hangs after using a while loop-CodePudding

I'm trying to make a program that is essentially an etchasketck, with some minor tweaks for my school project(the required use of a main function, wasd as movement controls, and q to quit the program and p to pick up or drop down the turtle pen). I was testing this code in trinket.io and it was working fine. You can see it working there with this link: https://trinket.io/python/99fd3ec305. However, when I go to run it from pycharm, cmd, or the python IDLE, it always leaves the turtle hanging and unresponsive. I get no errors, just the turtle to pop up for a few seconds, then it hangs, and I'm unable to do anything. Here's my code:

import sys
import turtle

arg_len = len(sys.argv)

# store length of arguments

if arg_len < 3:
    print("Too less arguments, using default values..")
    WIDTH = 200
    HEIGHT = 200
else:
    WIDTH = int(sys.argv[1])
    HEIGHT = int(sys.argv[2])

screen = turtle.Screen()
screen.setup(WIDTH, HEIGHT)
# create a turtle instance
t = turtle.Turtle()
t.speed(0)
# slow down the turtle
# declare flags
move = False
exit_flag = False


def up():
    global move
    move = True
    t.setheading(90)


def down():
    global move
    move = True
    t.setheading(270)


def left():
    global move
    move = True
    t.setheading(180)


def right():
    global move
    move = True
    t.setheading(0)


# toggle pen up and down
def toggle_pen():
    if t.isdown():
        t.penup()
    else:
        t.pendown()


# set exit flag
def quit_program():
    global exit_flag
    exit_flag = True


def check_border():
    if t.xcor() == WIDTH / 2:
        t.penup()
        t.setx(-WIDTH / 2)
    elif t.xcor() == -WIDTH / 2:
        t.penup()
        t.setx(WIDTH / 2)
    if t.ycor() == HEIGHT / 2:
        t.penup()
        t.sety(-HEIGHT / 2)
    elif t.ycor() == -HEIGHT / 2:
        t.penup()
        t.sety(HEIGHT / 2)


def listen_keys():
    screen.listen()
    screen.onkey(up, "w")
    screen.onkey(down, "s")
    screen.onkey(left, "a")
    screen.onkey(right, "d")
    screen.onkey(toggle_pen, "p")
    screen.onkey(quit_program, "q")


# main loop
def main():
    listen_keys()
    while not exit_flag:
        global move
        if move:
            t.forward(0.5)
            screen.update()
        check_border()
    else:
        t.done()

main()

I'm using python 3.10, and I mainly use pycharm for the running.

I was trying to get the turtle to move indefinitly without user input after the first user input, I was going to achieve this with the while loop, but it just leaves my program unresponsive. Can anyone tell me what's wrong that I'm not seeing?

CodePudding user response：

You've effectively put a while True: loop in an event-driven program where one should never be used. If I were writing this for the command line, with the constraints listed, I might go about it this way (dropping command line processing for example simplicity):

from turtle import Screen, Turtle

WIDTH, HEIGHT = 200, 200

def up():
    turtle.setheading(90)
    start_motion()

def down():
    turtle.setheading(270)
    start_motion()

def left():
    turtle.setheading(180)
    start_motion()

def right():
    turtle.setheading(0)
    start_motion()

def toggle_pen():
    if turtle.isdown():
        turtle.penup()
    else:
        turtle.pendown()

def quit_program():
    screen.bye()

def check_border():
    x, y = turtle.position()

    if x >= WIDTH / 2:
        turtle.penup()
        turtle.setx(-WIDTH / 2)
    elif x <= -WIDTH / 2:
        turtle.penup()
        turtle.setx(WIDTH / 2)

    if y >= HEIGHT / 2:
        turtle.penup()
        turtle.sety(-HEIGHT / 2)
    elif y <= -HEIGHT / 2:
        turtle.penup()
        turtle.sety(HEIGHT / 2)

def main():
    screen.onkey(up, 'w')
    screen.onkey(down, 's')
    screen.onkey(left, 'a')
    screen.onkey(right, 'd')

    screen.onkey(toggle_pen, 'p')
    screen.onkey(quit_program, 'q')

    screen.listen()
    screen.mainloop()

def move():
    turtle.forward(1)

    check_border()

    screen.ontimer(move, 25)

moving = False

def start_motion():
    global moving

    if not moving:
        moving = True
        move()

screen = Screen()
screen.setup(WIDTH, HEIGHT)

turtle = Turtle()
turtle.speed('fastest')

main()

See if this still works with trinket.io, IDLE and PyCharm, or if it can be made to do so.