Question

I am making a snake game which requires the player to press the WASD keys without stopping the game process to to get input from player. So I can’t use input() for this situation because then the game stops ticking to get input.

I found a getch() function which immediately gives input without pressing enter, but this function also stops game ticking to get input like input(). I decided to use threading module to get input via getch() in different thread. The problem is that getch() isn’t working while in different thread and I’m not sure why.

import threading, time
from msvcrt import getch

key = "lol" #it never changes because getch() in thread1 is useless

def thread1():
    while True:
        key = getch() #this simply is almost ignored by interpreter, the only thing it
        #gives is that delays print() unless you press any key
        print("this is thread1()")

threading.Thread(target = thread1).start()

while True:
    time.sleep(1)
    print(key)

So why getch() is useless when it is in thread1()?

Answer 1

The problem was that you’re creating a local variable key inside thread1 instead of overwriting the existing one. The quick-and-easy solution would be to declare key to be global inside thread1.

Finally, you should consider using locks. I don’t know if it’s necessary or not, but I’d imagine weird things could happen if you try and write a value to key in the thread while printing it out at the same time.

The working code:

import threading, time
from msvcrt import getch

key = "lol"

def thread1():
    global key
    lock = threading.Lock()
    while True:
        with lock:
            key = getch()

threading.Thread(target = thread1).start()

while True:
    time.sleep(1)
    print(key)