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()