On Tue, Sep 14, 2021 at 12:33:32PM -0700, Guido van Rossum wrote: > My view of this is: > > A. It's not an iterator if it doesn't define `__next__`. > > B. It is strongly recommended that iterators also define `__iter__`. > > In "standards" language, I think (A) is MUST and (B) is merely OUGHT or > maybe SHOULD.
That's not what the docs say :-) https://docs.python.org/3/library/stdtypes.html#iterator-types Part of the problem is that there are two kinds of thing that we call "iterator": 1. Objects that we implicitly or explicitly pass to `iter()` in order to return an interator object; they only need to define an `__iter__` method that returns the actual iterator object itself. (That's a slight simplification, because iter() will fall back on the Sequence Protocol if `__iter__` isn't defined. But to my mind, that makes Sequence Protocol objects *iterables* not iterators.) 2. Iterator objects themselves, which are defined by a protocol, not a type. The iterator object MUST define both `__iter__` and `__next__`, and the `__iter__` method MUST return self. -- Steve _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/RBM2IBQUKA6NGYIEW4WQRQ2EJ3I4OZY2/ Code of Conduct: http://python.org/psf/codeofconduct/
