在特定的時間量後更改變量python

Question

我需要能夠在特定時間段後切換布爾值，而其餘代碼仍照常運行。代碼的主要部分發生了什麼取決於Bool的值。

這是我的嘗試與goodguy的建議，但我仍然無法得到它的工作。當我打電話給班級時，「播放」切換爲True，但在2秒後不會切換回False，因此音調只播放一次。我究竟做錯了什麼？

class TimedValue: 

    def __init__(self): 
     self._started_at = datetime.datetime.utcnow() 

    def __call__(self): 
     time_passed = datetime.datetime.utcnow() - self._started_at 
     if time_passed.total_seconds() > 2: 
      return False 
     return True 

playing = False 
while True: 
    trigger = randint(0,10) # random trigger that triggers sound 
    if trigger == 0 and playing == False: 
    #play a tone for 2 seconds whilst the random triggers continue running 
    #after the tone is over and another trigger happens, the tone should play again 
     thread.start_new_thread(play_tone, (200, 0.5, 2, fs, stream,)) 
     value = TimedValue() 
     playing = value() 

    time.sleep(0.1) 

Answer 1

可以使用ThreadPool類從模塊multiprocessing：

import time 

myBool = False 

def foo(b): 
    time.sleep(30) #time in seconds 
    return not b 

from multiprocessing.pool import ThreadPool 

pool = ThreadPool(processes=1) 
result = pool.apply_async(foo,[myBool]) 

b = result.get() 

Answer 2

線程和多聽起來像這種情況下矯枉過正。另一種可能的方法是定義類似於可調用的類，它的實例記得一次在創造了測量：

import datetime 

class TimedValue: 

    def __init__(self): 
     self._started_at = datetime.datetime.utcnow() 

    def __call__(self): 
     time_passed = datetime.datetime.utcnow() - self._started_at 
     if time_passed.total_seconds() > XX: 
      return True 
     return False 

value = TimedValue() 

，並在使用時value()在其它代碼的部分可贖回