python通过线程实现定时器timer的源码

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import threading
def sayhello():
        print "hello world"
        global t        #Notice: use global variable!
        t = threading.Timer(5.0, sayhello)
        t.start()

t = threading.Timer(5.0, sayhello)
t.start()

运行结果如下

>python hello.py

hello world

hello world

hello world

下面是定时器类的实现：

class Timer(threading.Thread):
        """
        very simple but useless timer.
        """
        def __init__(self, seconds):
                self.runTime = seconds
                threading.Thread.__init__(self)
        def run(self):
                time.sleep(self.runTime)
                print "Buzzzz!! Time's up!"

class CountDownTimer(Timer):
        """
        a timer that can counts down the seconds.
        """
        def run(self):
                counter = self.runTime
                for sec in range(self.runTime):
                        print counter
                        time.sleep(1.0)
                        counter -= 1
                print "Done"

class CountDownExec(CountDownTimer):
        """
        a timer that execute an action at the end of the timer run.
        """
        def __init__(self, seconds, action, args=[]):
                self.args = args
                self.action = action
                CountDownTimer.__init__(self, seconds)
        def run(self):
                CountDownTimer.run(self)
                self.action(self.args)

def myAction(args=[]):
        print "Performing my action with args:"
        print args

if __name__ == "__main__":
        t = CountDownExec(3, myAction, ["hello", "world"])
        t.start()

以上代码在Python2.5.4中运行通过