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Ah, glad the mystery's solved! And sorry for the misdirection. On Sun, Dec 31, 2017 at 11:38 AM, Yahya Abou 'Imran < yahya-abou-imran@protonmail.com> wrote:
I guess a PR to fix the registry output would make sense (first file a bug onbugs.python.org for it).
Ok, I will!
Please don't hurry with this. I am going to rewrite ABCMeta in C soon. In fact most of the work is done but I am waiting for implementation of PEP 560 to settle (need few more days for this).
In the C version the caches/registry will be simpler and will not use WeakSet (instead they will be thin C wrappers around normal sets).
Ok, no problem.
Found out myself why the registry's empty: every iterator passed to Iterator.register() defines __iter__ and __next__, so they satisfy Iterator.__subclasshook__ and are added to the cache beforehand.
-- --Guido van Rossum (python.org/~guido)