[Python-Dev] Is explicit registration of Iterators needed? (original) (raw)

Serhiy Storchaka storchaka at gmail.com
Fri Oct 7 10:47:24 EDT 2016


On 07.10.16 17:37, Guido van Rossum wrote:

On Fri, Oct 7, 2016 at 6:36 AM, Serhiy Storchaka <storchaka at gmail.com> wrote:

A number of builtin iterator classes (but not all builtin iterator classes) are registered with the Iterator ABC in Lib/collectionsabc.py. But isinstance(it, Iterable) check works without explicit registration, because Iterable has subclasshook that checks iterator methods. Is there a need in explicit registrations? Or their can be safely removed? The preferred apprach is actually inheritance; registration comes next; the subclasshook is a final compromise to the tradition of duck typing. I think the registrations should stay.

Should we register missed builtin iterators? For example longrange_iterator.



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