16.2.7. Timer Objects

# The timer class was contributed by Itamar Shtull-Trauring

def Timer(*args, **kwargs):
    """Factory function to create a Timer object.

    Timers call a function after a specified number of seconds:

        t = Timer(30.0, f, args=[], kwargs={})
        t.start()
        t.cancel()     # stop the timer's action if it's still waiting

    """
    return _Timer(*args, **kwargs)

 

翻譯：Timer工廠函式，返回一個定時器物件，定時器物件負責呼叫函式，在指定的時間之後。

真正的定時器類：_Timer

class _Timer(Thread): #繼承Thread類
    """Call a function after a specified number of seconds:

            t = Timer(30.0, f, args=[], kwargs={})
            t.start()
            t.cancel()     # stop the timer's action if it's still waiting

    """

    def __init__(self, interval, function, args=[], kwargs={}): #重寫建構函式
        Thread.__init__(self) #呼叫父類建構函式
        self.interval = interval
        self.function = function
        self.args = args
        self.kwargs = kwargs
        self.finished = Event() #內部事件類，用來定時作用

    def cancel(self): #自定義cancel方法，取消定時器執行
        """Stop the timer if it hasn't finished yet"""
        self.finished.set()

    def run(self): #重寫run方法
        self.finished.wait(self.interval)
        if not self.finished.is_set():
            self.function(*self.args, **self.kwargs)
        self.finished.set()
 

演示：

import threading

def hello():
    print 'hello world!!!'



ti=threading.Timer(interval=3,function=hello)

ti.start()

執行結果：

C:\Python27\python.exe E:/pythonproj/基礎練習/t8.py
hello world!!!

Process finished with exit code 0