用Python编写简单的定时器的方法

下面介绍以threading模块来实现定时器的方法。

首先介绍一个最简单实现：

import threadingdef say_sth(str):  print str  t = threading.Timer(2.0, say_sth,[str])  t.start()if __name__ == '__main__':  timer = threading.Timer(2.0,say_sth,['i am here too.'])  timer.start()

不清楚在某些特殊应用场景下有什么缺陷否。

下面是所要介绍的定时器类的实现：

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()