2018-06-26 17:34 GMT+02:00 Franklin? Lee <leewangzhong+pyt...@gmail.com>: > Caller detects: The caller checks length before calling the dunder. If there > is no dunder, it doesn't check. Are there real-world cases where length is > not defined on an iterable collection?
Generators dont have a __len__ method. And they might have min/max that can be calculated without iterating over the entire thing. The builtin range() is an example. (but also an exception, since it does have a __len__ attribute. This is specifically part of range and not generators in general, though.). However, range() is an example where the dunders could be valuable - max(range(1e7)) already takes noticable time here, while it's rather easy to figure it out from start stop and step, just like len now does for it. _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
