Time-Limited Input

Time-Limited Input?

Interesting problem, this seems to work:

import time
from threading import Thread

answer = None

def check():
    time.sleep(2)
    if answer != None:
        return
    print("Too Slow")

Thread(target = check).start()

answer = input("Input something: ")

Timed user input in Python

You can use the Timer class for this purpose

from threading import Timer

timeout = 10
t = Timer(timeout, print, ['Sorry, times up!'])
t.start()
prompt = "You have %d seconds to answer the question. What color do cherries have?...\n" % timeout
answer = input(prompt)
t.cancel()

Output:

You have 10 seconds to answer the question. What color do cherries have?
(After 10 seconds)
Sorry, times up!

Input Time Limit

import time at the start of it, then:

...
if whichtasktodo == "Empty Garbage":
    start_time = time.time()
    ...
    end_time = time.time()
    if (emptygarbagetask = "Swipe Down") and (end_time - start_time <= 5):
        ...
...

Time limit for an input

import java.util.Timer;
import java.util.TimerTask;
import java.io.*;
public class test
{
    private String str = "";

    TimerTask task = new TimerTask()
    {
        public void run()
        {
            if( str.equals("") )
            {
                System.out.println( "you input nothing. exit..." );
                System.exit( 0 );
            }
        }    
    };

    public void getInput() throws Exception
    {
        Timer timer = new Timer();
        timer.schedule( task, 10*1000 );

        System.out.println( "Input a string within 10 seconds: " );
        BufferedReader in = new BufferedReader(
        new InputStreamReader( System.in ) );
        str = in.readLine();

        timer.cancel();
        System.out.println( "you have entered: "+ str ); 
    }

    public static void main( String[] args )
    {
        try
        {
            (new test()).getInput();
        }
        catch( Exception e )
        {
            System.out.println( e );
        }
        System.out.println( "main exit..." );
    }
}

How to set time limit on raw_input

The signal.alarm function, on which @jer's recommended solution is based, is unfortunately Unix-only. If you need a cross-platform or Windows-specific solution, you can base it on threading.Timer instead, using thread.interrupt_main to send a KeyboardInterrupt to the main thread from the timer thread. I.e.:

import thread
import threading

def raw_input_with_timeout(prompt, timeout=30.0):
    print(prompt, end=' ')    
    timer = threading.Timer(timeout, thread.interrupt_main)
    astring = None
    try:
        timer.start()
        astring = input(prompt)
    except KeyboardInterrupt:
        pass
    timer.cancel()
    return astring

this will return None whether the 30 seconds time out or the user explicitly decides to hit control-C to give up on inputting anything, but it seems OK to treat the two cases in the same way (if you need to distinguish, you could use for the timer a function of your own that, before interrupting the main thread, records somewhere the fact that a timeout has happened, and in your handler for KeyboardInterrupt access that "somewhere" to discriminate which of the two cases occurred).

Edit: I could have sworn this was working but I must have been wrong -- the code above omits the obviously-needed timer.start(), and even with it I can't make it work any more. select.select would be the obvious other thing to try but it won't work on a "normal file" (including stdin) in Windows -- in Unix it works on all files, in Windows, only on sockets.

So I don't know how to do a cross-platform "raw input with timeout". A windows-specific one can be constructed with a tight loop polling msvcrt.kbhit, performing a msvcrt.getche (and checking if it's a return to indicate the output's done, in which case it breaks out of the loop, otherwise accumulates and keeps waiting) and checking the time to time out if needed. I cannot test because I have no Windows machine (they're all Macs and Linux ones), but here the untested code I would suggest:

import msvcrt
import time

def raw_input_with_timeout(prompt, timeout=30.0):
    print(prompt, end=' ')    
    finishat = time.time() + timeout
    result = []
    while True:
        if msvcrt.kbhit():
            result.append(msvcrt.getche())
            if result[-1] == '\r':   # or \n, whatever Win returns;-)
                return ''.join(result)
            time.sleep(0.1)          # just to yield to other processes/threads
        else:
            if time.time() > finishat:
                return None

The OP in a comment says he does not want to return None upon timeout, but what's the alternative? Raising an exception? Returning a different default value? Whatever alternative he wants he can clearly put it in place of my return None;-).

If you don't want to time out just because the user is typing slowly (as opposed to, not typing at all!-), you could recompute finishat after every successful character input.

---

Related Topics