Path: csiph.com!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail From: Paul Rubin Newsgroups: comp.lang.python Subject: Re: Distinction between =?utf-8?B?4oCcY2xhc3PigJ0=?= and =?utf-8?B?4oCcdHlwZeKAnQ==?= Date: Fri, 13 May 2016 16:06:35 -0700 Organization: A noiseless patient Spider Lines: 16 Message-ID: <87r3d536dg.fsf@jester.gateway.pace.com> References: <85eg96eebr.fsf@benfinney.id.au> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: mx02.eternal-september.org; posting-host="52eac348160ce62b68e4635eee7cc854"; logging-data="24544"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX181RnwmLCWzBfli9PRfnA38" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) Cancel-Lock: sha1:ncChX/YbW4KANXhO4nm1tM7chjM= sha1:+JrbixXPYiddLO4P3jGmK1AKCdo= Xref: csiph.com comp.lang.python:108628 Terry Reedy writes: > I suspect that one could produce a class that is not a type, in > Guido's meaning, with a metaclass that is not a subclass of the type > class. I don't otherwise know what Guido might have meant. I think meant that if X is a class, then X is (usually) also a type; but the reverse is not true. We used to think of type and class as the same thing in practice. We didn't have to concern ourselves about too much about theoretical or pedantic differences that might exist. Now with PEP 484, the situation where X is a type but not a class is significant enough in practice that we have to be more careful about the distinction than we were in the Python 2 era. There may(?) also be situations where X is a class but not a type, but I don't think that's being considered as important as the other direction.