python - 用户输入超时，循环

Question

我正在尝试创建一个循环 python 函数，它执行任务并提示用户做出响应，如果用户在给定时间内没有响应，则序列将重复。

这大致基于这个问题:How to set time limit on raw_input

任务由 some_function() 表示。超时是以秒为单位的变量。以下代码有两个问题:

1. 无论用户是否提示，raw_input 提示在指定的 4 秒时间后都不会超时。

2. 当输入 'q' 的 raw_input 时(没有 '' 因为我知道输入的任何内容都会自 Action 为字符串输入)该函数不会退出循环。

`

import thread
import threading
from time import sleep

def raw_input_with_timeout():
    prompt = "Hello is it me you're looking for?"
    timeout = 4
    astring = None
    some_function()
    timer = threading.Timer(timeout, thread.interrupt_main)
    try:
        timer.start()
        astring = raw_input(prompt)
    except KeyboardInterrupt:
        pass
    timer.cancel()
    if astring.lower() != 'q':
        raw_input_with_timeout()
    else:
        print "goodbye"

`

Answer 1

警告:这旨在根据要求在 *nix 和 OSX 中工作，但绝对不会在 Windows 中工作。

我用过 this modification一个 ActiveState 配方作为下面代码的基础。它是一个易于使用的对象，可以读取超时输入。它使用轮询一次收集一个字符并模拟 raw_input()/input() 的行为。

超时输入

注意:显然下面的 _getch_nix() 方法不适用于 OP，但它适用于 OSX 10.9.5。你可能会调用 _getch_osx() 而不是运气好，尽管它似乎只在 32 位 python 中工作，因为 Carbon 不完全支持 64 位。

import sys
import time


class TimeoutInput(object):
    def __init__(self, poll_period=0.05):
        import sys, tty, termios  # apparently timing of import is important if using an IDE
        self.poll_period = poll_period

    def _getch_nix(self):
        import sys, tty, termios
        from select import select
        fd = sys.stdin.fileno()
        old_settings = termios.tcgetattr(fd)
        try:
            tty.setraw(sys.stdin.fileno())
            [i, o, e] = select([sys.stdin.fileno()], [], [], self.poll_period)
            if i:
                ch = sys.stdin.read(1)
            else:
                ch = ''
        finally:
            termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
        return ch

    def _getch_osx(self):
        # from same discussion on the original ActiveState recipe:
        # http://code.activestate.com/recipes/134892-getch-like-unbuffered-character-reading-from-stdin/#c2
        import Carbon
        if Carbon.Evt.EventAvail(0x0008)[0] == 0:  # 0x0008 is the keyDownMask
            return ''
        else:
            # The event contains the following info:
            # (what,msg,when,where,mod)=Carbon.Evt.GetNextEvent(0x0008)[1]
            #
            # The message (msg) contains the ASCII char which is
            # extracted with the 0x000000FF charCodeMask; this
            # number is converted to an ASCII character with chr() and
            # returned
            (what,msg,when,where,mod)=Carbon.Evt.GetNextEvent(0x0008)[1]
            return chr(msg & 0x000000FF)

    def input(self, prompt=None, timeout=None,
              extend_timeout_with_input=True, require_enter_to_confirm=True):
        """timeout: float seconds or None (blocking)"""
        prompt = prompt or ''
        sys.stdout.write(prompt)  # this avoids a couple of problems with printing
        sys.stdout.flush()  # make sure prompt appears before we start waiting for input
        input_chars = []
        start_time = time.time()
        received_enter = False
        while (time.time() - start_time) < timeout:
            # keep polling for characters
            c = self._getch_osx()  # self.poll_period determines spin speed
            if c in ('\n', '\r'):
                received_enter = True
                break
            elif c:
                input_chars.append(c)
                sys.stdout.write(c)
                sys.stdout.flush()
                if extend_timeout_with_input:
                    start_time = time.time()
        sys.stdout.write('\n')  # just for consistency with other "prints"
        sys.stdout.flush()
        captured_string = ''.join(input_chars)
        if require_enter_to_confirm:
            return_string = captured_string if received_enter else ''
        else:
            return_string = captured_string
        return return_string

测试一下

# this should work like raw_input() except it will time out
ti = TimeoutInput(poll_period=0.05)
s = ti.input(prompt='wait for timeout:', timeout=5.0,
             extend_timeout_with_input=False, require_enter_to_confirm=False)
print(s)

重复输入

这实现了我理解的你的初衷。我认为进行递归调用没有任何值(value) - 我认为您想要的只是重复输入？如有不妥请指正。

ti = TimeoutInput()
prompt = "Hello is it me you're looking for?"
timeout = 4.0
while True:
    # some_function()
    s = ti.input(prompt, timeout)
    if s.lower() == 'q':
        print "goodbye"
        break