python - Time-Limited Input?

Question

This question already has answers here:

Answer 1

If it is acceptable to block the main thread when user haven't provided an answer:

from threading import Timer

timeout = 10
t = Timer(timeout, print, ['Sorry, times up'])
t.start()
prompt = "You have %d seconds to choose the correct answer...
" % timeout
answer = input(prompt)
t.cancel()

Otherwise, you could use @Alex Martelli's answer (modified for Python 3) on Windows (not tested):

import msvcrt
import time

class TimeoutExpired(Exception):
    pass

def input_with_timeout(prompt, timeout, timer=time.monotonic):
    sys.stdout.write(prompt)
    sys.stdout.flush()
    endtime = timer() + timeout
    result = []
    while timer() < endtime:
        if msvcrt.kbhit():
            result.append(msvcrt.getwche()) #XXX can it block on multibyte characters?
            if result[-1] == '
':
                return ''.join(result[:-1])
        time.sleep(0.04) # just to yield to other processes/threads
    raise TimeoutExpired

Usage:

try:
    answer = input_with_timeout(prompt, 10)
except TimeoutExpired:
    print('Sorry, times up')
else:
    print('Got %r' % answer)

On Unix you could try:

import select
import sys

def input_with_timeout(prompt, timeout):
    sys.stdout.write(prompt)
    sys.stdout.flush()
    ready, _, _ = select.select([sys.stdin], [],[], timeout)
    if ready:
        return sys.stdin.readline().rstrip('
') # expect stdin to be line-buffered
    raise TimeoutExpired

Or:

import signal

def alarm_handler(signum, frame):
    raise TimeoutExpired

def input_with_timeout(prompt, timeout):
    # set signal handler
    signal.signal(signal.SIGALRM, alarm_handler)
    signal.alarm(timeout) # produce SIGALRM in `timeout` seconds

    try:
        return input(prompt)
    finally:
        signal.alarm(0) # cancel alarm