Best way to close the program pressing Esc anytime the user wants?

Question

Which is the best way to close a program anytime by pressing Esc? I need to implement this thing in an important code, but my experiments didn't work.

This is the last one:

from multiprocessing import Process
import keyboard
import sys


def stop_anytime():
    bool = True
    while bool:
        try:
            if keyboard.is_pressed('Esc'):
                sys.exit()
                bool = False
        except:
            break

def print_numbers():
    for n in range(150000):
        print(n)
 

if __name__ == '__main__':
    p1 = Process(target=stop_anytime)
    p2 = Process(target=print_numbers)
    p1.start()
    p2.start()

btw, don't use `bool` as the name of a variable, it is a built-in function. — quamrana, Oct 28 '20 at 09:12
@quamrana: `bool` is the name of a built-in *`class`* — but you're right about not using it as the name of a variable. — martineau, Oct 28 '20 at 09:36
Ok, the documentation calls it both a class and a function. I thought I'd check before commenting and I found [built-in function bool()](https://docs.python.org/3/library/stdtypes.html#boolean-values) — quamrana, Oct 28 '20 at 09:37
This [documentation](https://docs.python.org/3/library/functions.html#bool) says it's a class — although classes _are_ callable in Python… — martineau, Oct 28 '20 at 09:41

score 0 · Answer 1 · edited Oct 28 '20 at 09:21

0

edit: this works:

import keyboard
import sys

def print_numbers():
    for n in range(150000):
        print(n)
        if keyboard.is_pressed('Esc'):
            sys.exit()


if __name__ == '__main__':
    print_numbers()

you have to join the processes like this:

p1.join()
p2.join()

or maybe that has to be done with threading only

also you maybe could do this:

def print_numbers():
    for n in range(150000):
        print(n)
        if keyboard.is_pressed('Esc'):
            sys.exit()

or possibly even use pygame module for the code above to register key presses

edited Oct 28 '20 at 09:21

quamrana

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answered Oct 28 '20 at 09:01

Matiiss

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Ok, this works with that example, but I need to be able to quit anytime I want. Meaning that I have a longer function with a selenium webdriver working and I want to be able to quit even when webdriver is searching on the web. This is why I thought to use processes – Matt Oct 28 '20 at 10:55

martineau · Accepted Answer · 2020-10-28T11:19:50.373

0

The keyboard module is multithreaded, so you don't need to use the multiprocessing module yourself to do this. I think the cleanest way to do things would be to use the keyboard.hook() function to specify a callback function that does what's needed.

Note: Since this callback will be invoked from a separate keyboard thread, calling sys.exit() in it will only exit that, not the whole program/process. To accomplish that you need to call os._exit() instead.

import keyboard
import os


def exit_on_key(keyname):
    """ Create callback function that exits current process when the key with
        the given name is pressed.
    """
    def callback(event):
        if event.name == keyname:
            os._exit(1)
    return callback


def print_numbers():
    for n in range(150000):
        print(n)


if __name__ == '__main__':

    keyboard.hook(exit_on_key('esc'))
    print_numbers()

edited Oct 28 '20 at 11:19

answered Oct 28 '20 at 11:01

martineau

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It doesn't work: it says me that exit_on_key and keyname are not defined – Matt Oct 28 '20 at 20:28
I can only assume you're somehow not running the code in my answer, because not only does it work for me, there's no explanation I can think of to explain the errors you're encountering. – martineau Oct 28 '20 at 20:46
My fault, you're completely right sorry. Thanks for all! – Matt Oct 28 '20 at 20:56

Best way to close the program pressing Esc anytime the user wants?

2 Answers2