steven probably knows this, but to flag the issue for people who are looking at generators/coroutines for the first time: there's a little "gotcha" about exactly how the two sides of the conversation are synchronized. in simple terms: send also receives.
unfortunately the example steven gave doesn't really show this, so i've modified it below. you can now see that the first next() after .send() receives 2, not 1. note that i am using python 3, so the .next() method is .__next__() (the asymmetry between next and send seems odd to me, but there you go). (in a sense this is completely logical, but if you're used to the asynchronous way the internet works, it can seem unintuitive) how to handle this was one of the things the original post was asking about (if i understood correctly). >>> def gen(n): ... while True: ... obj = yield n ... n += 1 ... if obj is not None: n = obj ... >>> g = gen(5) >>> next(g) 5 >>> g.__next__() 6 >>> g.send(1) 1 >>> next(g) 2 andrew Steven D'Aprano wrote: > On Tue, 10 Feb 2009 05:28:26 +0000, John O'Hagan wrote: >> I would love to see a simple code example of this if you have one; I've >> been wanting to do this but couldn't even get started. > > Is this too simple? > >>>> def gen(n): > ... while True: > ... obj = yield n > ... if obj is not None: n = obj > ... >>>> g = gen(5) >>>> g.next() > 5 >>>> g.next() > 5 >>>> g.send(12) > 12 >>>> g.next() > 12 -- http://mail.python.org/mailman/listinfo/python-list
