loop until key is pressed and repeat

Question

Im trying to loop a print when a key is pressed and stop when another key is pressed.

Also I dont want to exit the program, it must continue listening for a key.

Problem: But what I get is a infinite loop because it cant listen to a another key while loop is True!

from pynput import keyboard
    
def on_press(key):
    if key == keyboard.Key.f9:
        while True:
            print("loading")
    if key == keyboard.Key.f10:
        # Stop listener
        return False

# Collect events until released
with keyboard.Listener(on_press=on_press) as listener:
    listener.join()

Im using pynput, docs here

EDIT

I did explained wrong one part, I wanted to do a loop when a certain key WAS pressed.

Answer 1

You can't run while True (or any long-running function) inside on_press
because it blocks Listener. You have to run it in separated thread.

You need on_press to create and start thread.
And on_release to stop thread.
It needs global variable. ie. running for this.

I use datetime only to see if it displays new line or not.

from pynput import keyboard
import threading
import datetime

# --- functions ---

def loading():
    while running:
         print("loading", datetime.datetime.now()) #, end='\r')
    
def on_press(key):
    global running  # inform function to assign (`=`) to external/global `running` instead of creating local `running`

    if key == keyboard.Key.f9:
        running = True
        # create thread with function `loading`
        t = threading.Thread(target=loading)
        # start thread
        t.start()
        
    if key == keyboard.Key.f10:
        # stop listener
        return False

def on_release(key):
    global running  # inform function to assign (`=`) to external/global `running` instead of creating local `running`
    
    if key == keyboard.Key.f9:
        # to stop loop in thread
        running = False
        
#--- main ---

with keyboard.Listener(on_press=on_press, on_release=on_release) as listener:
    listener.join()