非阻塞raw_input

今天从Gary Robinson的博客看到的，设置raw_input输入的超时时间，觉得挺实用的。代码如下：

#!/usr/bin/env python


import signal

class AlarmException(Exception):
    pass
    
def alarmHandler(signum, frame):
    raise AlarmException

def nonBockingRawInput(prompt='', timeout=20):
    signal.signal(signal.SIGALRM, alarmHandler)
    signal.alarm(timeout)
    try:
        text = raw_input(prompt)
        signal.alarm(0)
        return text
    except AlarmException:
        print 'Prompt timeout. Continuing...'
    signal.signal(signal.SIGALRM, signal.SIG_IGN)

    return ''