generator - Understand the producer and receiver using coroutine in python -

i want use coroutine implement producer , receiver. idea using 2 coroutines , 1 producer , 1 recevier. understand coroutine's send , running mode wrong. here code :

def coroutine(func):     def start(*args,**kwargs):         cr = func(*args,**kwargs)         cr.next()         return cr     return start  class producer(object):     def __init__(self, recevier):         self.count=1         self.producer_coroutine = self._producer()         self.receiver = receiver      @coroutine     def _producer(self):         print "waiting"         yield          while true:             self.send("yeah, no, yeah, no")             get_feedback =  (yield )             print ("get feedback %s"%get_feedback)             self.send("a series of tubes")             break      def send(self,arg):         self.receiver.receive_coroutine.send(arg)      def init_producer(self):          self.producer_coroutine.send("begin send , receive")  class recevier(object):     def __init__(self):         self.count=1         self.receive_coroutine=self._rececive()         self.producer = none      def setting_producer(self, producer):         self.producer = producer      @coroutine     def _rececive(self):         while true:             line = (yield)             print("get line : %s" %line)             self.feedback("got it")      def feedback(self, arg):         self.producer.producer_coroutine.send(arg)   receiver = recevier() producer = producer(receiver) receiver.setting_producer(producer) producer.init_producer() 

python give me error:

waiting line : yeah, no, yeah, no traceback (most recent call last):   file "test/test_coroutine.py", line 56, in <module>     producer.init_producer()   file "test/test_coroutine.py", line 31, in init_producer     self.producer_coroutine.send("begin send , receive")   file "test/test_coroutine.py", line 21, in _producer     self.send("yeah, no, yeah, no")   file "test/test_coroutine.py", line 28, in send     self.receiver.receive_coroutine.send(arg)   file "test/test_coroutine.py", line 47, in _rececive     self.feedback("got it")   file "test/test_coroutine.py", line 50, in feedback     self.producer.producer_coroutine.send(arg) valueerror: generator executing 

update: find greenlet may implement communication. :

from greenlet import greenlet  def test1():     global     print 12, "begin switch"     gr2.switch()     = 4     print " begin  switch too"     gr2.switch()  def test2():      global     print 56,"come test1, swich"     gr1.switch()     print     print 78  a=5 gr1 = greenlet(test1) gr2 = greenlet(test2) gr1.switch() 

when call producer.init_producer(), following happens:

• _producer sends "yeah, no, yeah, no".
• _rececive receives "yeah, no, yeah, no" , prints it.
• _rececive calls self.feedback.
• self.feedback sends "got it" _producer
• however, _producer still @ line self.send("yeah, no, yeah, no"), because _rececive has not yielded yet.
• as _producer not on yield statement, cannot receive send, , exception thrown.

therefore, problem feedback loop. i'm not sure why feedback loop needed, if comment out send_feedback , get_feedback lines, program works fine, producing:

waiting line : yeah, no, yeah, no line : series of tubes traceback (most recent call last):   file "d.py", line 58, in <module>     producer.init_producer()   file "d.py", line 32, in init_producer     self.producer_coroutine.send("begin send , receive") stopiteration