在未收到用户输入的情况下执行某些操作 [英] Do something while user input not received

问题描述

在Python中，当用户未提供输入时，我可以用什么方式循环执行某些操作.我有python客户端，我要求用户输入，但是当用户未提供输入时，我想保持每五秒钟进行一次更新.

In Python, in what way can I do something on loop while user has not given an input. I have python client and I ask for user input, but while user has not given an input I'd like to keep giving updates every five second.

我不能使用

 while (raw_input==""):
      update()

因为如果输入为"，则表示用户已经输入了某些内容(按回车键)；

since if input is "", it means user already entered something (hit enter);

有办法吗?

更新:

我仍然无法为我工作.我尝试了以下方法，也尝试了与此线程类似的方法:等待用户输入在单独的线程中.而且，我还尝试改为将update()方法传递给应该在后台运行的线程.但是任何使用raw_input()的东西都会使其停留在等待输入的状态:

I still can't get anything to work for me. I tried the method below, also tried something similar to this thread: waiting for user input in separate thread. And I also tried instead passing an update() method to the thread that's supposed to be working in the background. But anything with raw_input() makes it stuck on waiting for input:

 import threading
 import time

def update():
   while True:
      time.sleep(5)
      print "update"+'\n'

mythread = threading.Thread(target=update, args=())
mythread.daemon = True
mythread.start()

while True:
   usrin=raw_input()
   print "you typed: "+usrin

每次用户输入内容时，都会完成更新，然后将usrin退还给用户.如果这是我想要的，我可以轻松地将update()放入最后一个while循环.

Every time user inputs something, update is done and then usrin is given back. If this was what I wanted I could just easily put the update() into the last while loop.

如果我只是使用update方法启动此线程，而在程序中什么也不做(取消最后一个while循环)，那么在shell中，它每五秒钟更新一次，我仍然可以使用shell(即键入3 + 5)它给了我8).我希望在程序中发生这样的事情，即当用户处于非活动状态时更新，并且如果他输入了响应并返回到更新.

If I were to just start this thread with update method and do nothing else in the program (scrap the last while loop), then in shell while it updates every five seconds I can still use the shell (i.e type 3+5 and it gives me 8). I want something like that to happen within the program, when user is inactive update, and if he types react and go back to updating.

注意:另外，我目前正在使用python 2.7.8，切换版本会有所帮助吗?

NOTE: Also, I'm currently using python 2.7.8, would switching versions help?

推荐答案

也许这可以帮助您入门:

Maybe this can get you started:

from threading import Thread
from time import sleep

result = None

def update_every_second():
    while result is None:
        sleep(1)
        print "update"

t = Thread(target=update_every_second)
t.start()
result = raw_input('? ')

print "The user typed", result

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