[Python-Dev] Is explicit registration of Iterators needed?

[Guido van Rossum]

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/_collections_abc.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.

-- 
--Guido van Rossum (python.org/~guido)