On Fri, Nov 21, 2014 at 8:47 AM, Antoine Pitrou <[email protected]> wrote:
> On 2014年11月21日 05:47:58 -0800 > Raymond Hettinger <[email protected]> wrote: > > > > Another issue is that it breaks the way I and others have taught for > years that generators are a kind of iterator (an object implementing the > iterator protocol) and that a primary motivation for generators is to > provide a simpler and more direct way of creating iterators. However, > Chris explained that, "This proposal causes a separation of generators and > iterators, so it's no longer possible to pretend that they're the same > thing." That is a major and worrisome conceptual shift. > > I agree with Raymond on this point. > Pretending they're the same thing has always been fraught with subtle errors. From the *calling* side a generator implements the same protocol as any other iterator (though it also has a few others -- send(), throw(), close()). However *inside* they are not at all similar -- generators produce a value is done through "yield", __next__() methods use return. Even if we end up rejecting the PEP we should campaign for better understanding of generators. Raymond may just have to fix some of his examples. -- --Guido van Rossum (python.org/~guido)
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