Python 3和Windows 7的定时输入

Question

我正在寻找一种解决方案，以便在一定时间后使用户的输入超时。此代码应在5秒钟后打印“成功...”，而无需用户进行任何交互：

def input_with_timeout(timeout):

    print ("Hello, you can type and press enter to change 'ans' variable value or wait "+str(timeout)+" seconds and the program will continue")   
    ans=input()   #pass input after timeout
    return ans


s="mustnotchange"

s=input_with_timeout(5)

if s=="mustnotchange":
    print("Success, if you didn't just cheat by writing mustnotchange")
else:
    print("you answered : "+s+" variable value has changed")

我知道这个问题经常被问到，但是以下主题中提供的NONE解决方案在WINDOWS 7和Python 3（Windows 7“最终” SP1 64位和Python 3.6.8 64位）上有效。Python 3 Timed Input

How to set time limit on raw_input

Keyboard input with timeout?

raw_input and timeout

实际上，我正在使用“技巧”来避免这个问题：我使用os.startfile（）启动了另一个python脚本，但是启动时它无法对输入做出反应。

如果没有任何可行的答案，做到这一点一定很困难（多处理，线程，队列...，但这在很多情况下肯定会有所帮助。

谢谢。

Answer 1

once进行跨平台提示超时。超时时，它将要求用户按Enter键，因此提示-线程可以干净地关闭。

删除影响_prompter_exit的部分将允许超时恢复而无需用户按下Enter键，其代价是使提示线程保持活动状态，直到整个过程退出为止。仅像@Mad Physicist建议的那样加入具有超时的提示线程是行不通的，因为它不会取消对input()调用本身的阻止。如果不使用特定于OS的库，则（AFAIK）无法在没有最终提供某种形式的输入的情况下唤醒等待input()的线程。

代码是我的答案的简化版本，允许在给定的时间范围内进行多次输入：

Taking in multiple inputs for a fixed time in Python

from threading import Thread, enumerate, Event
from queue import Queue, Empty
import time


SENTINEL = None


class PromptManager(Thread):

    def __init__(self, timeout):
        super().__init__()
        self.timeout = timeout
        self._in_queue = Queue()
        self._out_queue = Queue()
        self.prompter = Thread(target=self._prompter, daemon=True)
        self._prompter_exit = Event()

    def run(self):
        """Run worker-thread. Start prompt-thread, fetch passed
        input from in_queue and forward it to `._poll()` in MainThread.
        If timeout occurs before user-input, enqueue SENTINEL to
        unblock `.get()` in `._poll()`.
        """
        self.prompter.start()
        try:
            txt = self._in_queue.get(timeout=self.timeout)
        except Empty:
            self._out_queue.put(SENTINEL)
            print(f"\n[{time.ctime()}] Please press Enter to continue.")
            # without usage of _prompter_exit() and Enter, the
            # prompt-thread would stay alive until the whole program ends
            self._prompter_exit.wait()
        else:
            self._out_queue.put(txt)

    def start(self):
        """Start manager-thread."""
        super().start()
        return self._poll()

    def _prompter(self):
        """Prompting target function for execution in prompter-thread."""
        self._in_queue.put(input(f"[{time.ctime()}] >$ "))
        self._prompter_exit.set()

    def _poll(self):
        """Get forwarded inputs from the manager-thread executing `run()`
        and process them in the parent-thread.
        """
        msg =  self._out_queue.get()
        self.join()
        return msg

用于演示：

if __name__ == '__main__':

    pm = PromptManager(timeout=5)
    msg = pm.start()
    print(f"User input: {msg}")

    for i in range(3):
        print(f"[{time.ctime()}] Do something else. "
              f"Alive threads:{[t.name for t in enumerate()]}")
        time.sleep(1)

以触发超时运行：

[Tue Nov 26 20:50:47 2019] >$ 
[Tue Nov 26 20:50:52 2019] Please press Enter to continue.

User input: None
[Tue Nov 26 20:50:57 2019] Do something else. Alive threads:['MainThread']
[Tue Nov 26 20:50:58 2019] Do something else. Alive threads:['MainThread']
[Tue Nov 26 20:50:59 2019] Do something else. Alive threads:['MainThread']

Process finished with exit code 0

及时运行用户输入：

[Tue Nov 26 20:51:16 2019] >$ Hello
User input: Hello
[Tue Nov 26 20:51:19 2019] Do something else. Alive threads:['MainThread']
[Tue Nov 26 20:51:20 2019] Do something else. Alive threads:['MainThread']
[Tue Nov 26 20:51:21 2019] Do something else. Alive threads:['MainThread']

Process finished with exit code 0

最后，我修改了
@@ Darkonaut答案（谢谢！）
以匹配我的第一种情况，并在库pynput中添加了“模拟键盘”以自动按下“ Enter”。
请注意，这在终端机（Python 3.6.8和Windows 7 SP1）中有效，但是如果从IDLE开始，则不起作用。from threading import Thread, enumerate, Event
from queue import Queue, Empty
import time
from pynput.keyboard import Key, Controller


SENTINEL = None


class PromptManager(Thread):

    def __init__(self, timeout):
        super().__init__()
        self.timeout = timeout
        self._in_queue = Queue()
        self._out_queue = Queue()
        self.prompter = Thread(target=self._prompter, daemon=True)
        self._prompter_exit = Event()

    def run(self):
        """Run worker-thread. Start prompt-thread, fetch passed
        input from in_queue and forward it to `._poll()` in MainThread.
        If timeout occurs before user-input, enqueue SENTINEL to
        unblock `.get()` in `._poll()`.
        """
        self.prompter.start()
        try:
            txt = self._in_queue.get(timeout=self.timeout)
        except Empty:
            self._out_queue.put(SENTINEL)
            print(f"\n[{time.ctime()}] Please press Enter to continue.")
            # without usage of _prompter_exit() and Enter, the
            # prompt-thread would stay alive until the whole program ends
            keyboard = Controller()
            keyboard.press(Key.enter)
            keyboard.release(Key.enter)
            self._prompter_exit.wait()

        else:
            self._out_queue.put(txt)

    def start(self):
        """Start manager-thread."""
        super().start()
        return self._poll()

    def _prompter(self):
        """Prompting target function for execution in prompter-thread."""
        self._in_queue.put(input(f"[{time.ctime()}] >$ "))
        self._prompter_exit.set()

    def _poll(self):
        """Get forwarded inputs from the manager-thread executing `run()`
        and process them in the parent-thread.
        """
        msg =  self._out_queue.get()
        self.join()
        return msg



def input_with_timeout(default, timeout):

    print ("Hello, you can type and press enter to change 'ans' variable value or wait "+str(timeout)+" seconds and the program will continue")   
    pm = PromptManager(timeout)
    ans= pm.start()
    if isinstance(ans, str):
        print("ok")
        return ans
    else:
        return default



s="mustnotchange"

s=input_with_timeout(s,5)

if s=="mustnotchange":
    print("Success, if you didn't just cheat by writing mustnotchange")
else:
    print("you answered : "+s+" variable value has changed")

time.sleep(5)

Answer 2

@@ Darkonaut答案（谢谢！）