用Python编写简单的定时器的方法

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()

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()