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 threading

def 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()