Stopping the execution of Python script

Question

I have written this question after reading this question and this other one. I would like to stop the execution of a Python script when a button is pressed. Here the code:

import turtle
from sys import exit

def stop_program():
    print("exit function")
    exit(0) #raise SystemExit(0) gives the same result
    print("after the exit function")

# Create keyboard binding
turtle.listen()
turtle.onkey(stop_program, "q")

# Main function
while True:
    # Code: everything you want

If I press the button "q" (even muliple time) the output is:

exit function
exit function
exit function
exit function
exit function
exit function
exit function
...

i.e. one line every time I press. This means that the exit works for the function and not for the whole program. Any suggestion?

have you tried turtle.bye instead of your stop_program function? docs.python.org/3.3/library/… — Andrew
– Andrew, Commented Jan 4, 2019 at 14:23
trying now, however, what I wrote should work. The question is: why it exit from the function and not from the script execution? it is not a "return" — Leos313
– Leos313, Commented Jan 4, 2019 at 14:33
@Andrew: it exists but with some errors (it seems because of it is executing something else in the middle) — Leos313
– Leos313, Commented Jan 4, 2019 at 14:38
Can I see what you have under while True:? Do you happen to do except:\n anywhere? — user2201041
– user2201041, Commented Jan 4, 2019 at 14:57
I have found why this happens: "Since exit() ultimately “only” raises an exception, it will only exit the process when called from the main thread, and the exception is not intercepted.". I am investigating to find a "clean" solution (details from the sys module documentation) — Leos313
– Leos313, Commented Jan 4, 2019 at 15:21

mikeg · Accepted Answer · 2019-01-04 14:38:53Z

2

Dont use the while loop, use turtle.mainloop()

import turtle
from sys import exit

def stop_program():
    print("exit function")
    exit(0) #raise SystemExit(0) gives the same result
    print("after the exit function")

# Create keyboard binding
turtle.listen()
turtle.onkey(stop_program, "q")


turtle.mainloop()

That seems to work fine for me, give it a try.

answered Jan 4, 2019 at 14:38

mikeg

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2 Comments

Leos313 Over a year ago

where is the definition of turtle.mainloop()? where I can insert my instruction? I will try to find more info surfing on google

mikeg Over a year ago

it is built into turtle, docs.python.org/3.1/library/turtle.html#turtle.mainloop

Ticu Bogdan · Accepted Answer · 2019-01-06 08:20:19Z

-1

Try to use: sys.exit(), see if that works. Below code worked for me.

import turtle
import sys

def stop_program():
 print("exit function")
 sys.exit() #raise SystemExit(0) gives the same result
 print("after the exit function")


 # Create keyboard binding
 turtle.listen()
 turtle.onkey(stop_program, "q")
 turtle.mainloop()

edited Jan 6, 2019 at 8:20

answered Jan 4, 2019 at 14:25

Ticu Bogdan

12 bronze badges

5 Comments

Leos313 Over a year ago

of course no: from sys import exit allow to write just exit instead of sys.exit(). It is the same, isn't it?

Ticu Bogdan Over a year ago

import sys and then use sys.exit(). It woks for me fine. Used mikeg's code above, but adapted it a bit with my suggestion.

Leos313 Over a year ago

did you try the code that I wrote in the question? and it works? really?

Leos313 Over a year ago

It does not work. Try the code in the question please

Ticu Bogdan Over a year ago

I edited my solution to show you what worked for me. Have a look and let me know.

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