My program crashes after i hold the w key to move the turtle for too long in the turtle library

Question

The code is as follows:

import turtle

width = 400
length = 300

wn = turtle.Screen()
wn.bgcolor("black")
wn.title("x")

drawer = turtle.Turtle()
drawer.speed(3)
drawer.begin_fill()
drawer.color("blue", "yellow")

def drawern():
    drawer.seth(90)
    drawer.fd(1)

def drawerw():
    drawer.seth(180)
    drawer.fd(1)

def drawers():
    drawer.seth(270)
    drawer.fd(1)

def drawere():
    drawer.seth(0)
    drawer.fd(1)

wn.onkeypress(drawern, "w")
wn.onkeypress(drawerw, "a")
wn.onkeypress(drawers, "s")
wn.onkeypress(drawere, "d")

wn.listen()

wn.mainloop()

It gives a stack overflow error. Does anyone know why this issue persists? It doesn't happen when i let go of it once in a while.

Answer 1

I believe the stack overflow error is due to repeated assigning of angle to the stack. To prevent this, you can introduce a debounce. We will name our debounce as move. A debounce, in simple terms, is fail-safe to prevent an event for triggering again and again while keeping the rest of the code running.

Define the variable in global space:

move = False

As for the function:

def drawern():
    global move #To let the function know the variable is from global scope

    if not move: #The key is pressed first time
        drawer.seth(90)
        move = True #Sets our debounce to True, it will not activate until the key is released
        
    drawer.fd(1)

wn.onkeypress(drawern, "w")

We need to have another function with an event to reset our debounce:

def reset_db():
    global move
    move = False #Resets the debounce, referencing the key has been released

wn.onkeyrelease(reset_db, "w") #Connects the event

I have demonstrated for w key here only. You can duplicate it for the rest of the keys too.