On Friday, March 13, 2015 at 9:00:17 AM UTC+5:30, Steven D'Aprano wrote: > Rustom Mody wrote: > > > On Thursday, March 12, 2015 at 11:25:32 PM UTC+5:30, Marko Rauhamaa wrote: > >> Rustom Mody : > >> > >> > I guess we need > >> > 1. A clear ontology of the base concepts (which is a buzzword for > >> > nailed-down terminology) > >> > >> According to the documentation, a function whose definition contains a > >> yield statement is a generator: > >> > >> Using a yield expression in a function's body causes that function to > >> be a generator. > >> > >> <URL: https://docs.python.org/3/reference/expressions.html#yield-exp > >> ressions> > >> > >> generator > >> A function which returns an iterator. > >> > >> <URL: https://docs.python.org/3/glossary.html#term-generator> > >> > >> Apparently, what we have here is a discrepancy between the documentation > >> and the CPython implementation. > >> > >> In a word, it's a bug (somewhere). > > > > Throwing out some thought for better terminology. > > [Yeah needs to be chewed on a bit...] > > > > With respect to my example above: > > > > def foo(x): > > yield x+1 > > yield x+2 > > > > > > g = foo(2) > > > > Generator-instance: g > > Generator-factory: foo > > Generator: Concept in python (ontology) elaborated in terms of the above > > I think that is is reasonable.
Good that we agree! > Where the distinction is clear, or not important, than calling both g and > foo "generators" is acceptable shorthand. I realise that can be confusing > to beginners, but jargon often is confusing to beginners until they have > learned enough to be able to correctly interpret things in context. I would prefer -- when shortforming is required: generator-instance -> instance generator-factory -> factory rather than generator-instance -> generator generator-factory -> generator Yeah that can quarrel with the more usual OO notion of instance, but I find that ambiguity more remote > > > > Situation with coroutines is worse > > [Or I cant think of good terms...] > > Not really. The difference between a coroutine and a generator is mostly in > usage, that is, intent. They both use the same type, they both have send > methods, they both are generated the same way. If you are foolish, you can > even mix generator-behaviour and coroutine-behaviour in the same function: > > > py> def g(): > ... yield 1 > ... yield 2 > ... x = yield 3 > ... yield x + 1000 > ... > py> a = g() > py> next(a) > 1 > py> next(a) > 2 > py> next(a) > 3 > py> a.send(99) > 1099 > > But don't do that. > > So as far as Python is concerned, a coroutine is just a generator instance > which you use in a particular way, not a different kind of object. So I > would use similar terminology: > > A generator function/factory returns a generator instance, which we use as a > coroutine, so we can call it a coroutine. I think coroutines are intended to be symmetric in a way that generators are not. The nut-n-bolts of both may involve using yield but conceptually I find them different. And even there I would expect generators to close with StopIteration Whereas I would expect coroutines to close (on close method) with GeneratorExit [Ive not thought all this through properly so may be off the mark] -- https://mail.python.org/mailman/listinfo/python-list
