Python Timer.cancel() 方法

cancel() 是 Python 中线程模块的 Timer 类的内置方法。

Timer 类对象代表必须在给定时间过后才能执行的操作。这个类是Thread类的子类。该类中的 Cancel() 方法用于停止定时器和取消定时器对象的执行。只有当计时器仍在等待区域时,动作才会停止。

模块:

    from threading import Timer

用法:

    cancel()

参数:

• None

返回值:

这个方法的返回类型是<class 'NoneType'>.该方法不返回任何内容。它用于在线程等待期间取消线程。

范例1:

# python program to explain the# use of cancel() method in Timer classimport threadingdef helper_function(i):  print("Value printed=",i)if __name__=='__main__':      thread1 = threading.Timer(interval = 3, function = helper_function,args = (9,))  print("Starting the timer object")  print()    # Starting the function after 3 seconds  thread1.start()    print("This gets printed before the helper_function as helper_function starts after 3 seconds")  print()    # This cancels the thread when 3 seconds   # have not passed  thread1.cancel()  print("Thread1 cancelled, helper_function is not executed")

输出:

Starting the timer objectThis gets printed before the helper_function as helper_function starts after 3 secondsThread1 cancelled, helper_function is not executed

范例2:

# python program to explain the# use of cancel() method in Timer classimport threadingimport timedef helper_function(i):  print("Value printed=",i)  print()  if __name__=='__main__':      thread1 = threading.Timer(interval = 3, function = helper_function,args = (19,))  print("Starting the timer object")  print()    # Starting the function after 3 seconds  thread1.start()  # Sleeping this thread for 5 seconds  time.sleep(5)    # This will not cancel the thread as 3 seconds have passed  thread1.cancel()  print("This time thread is not cancelled as 3 seconds have passed when cancel() method is called")

输出:

Starting the timer objectValue printed= 19This time thread is not cancelled as 3 seconds have passed when cancel() method is called