On Wed, Mar 01, 2017 at 07:02:23AM +0800, 语言破碎处 wrote: > > where we use types? > almost: > isinstance(obj, T); > # issubclass(S, T); > > Note that TYPE is SET;
What does that mean? I don't understand. > if we add __contains__ and __le__ into "type", > then things become: > obj in T; But obj is **not** in T, since T is a type, not a container. "is-a" tests are not the same as "in" tests. They are completely unrelated comparisons. http://www.w3resource.com/java-tutorial/inheritance-composition-relationship.php The Wikipedia page on is-a is terribly complicated, but folks may get something from it: https://en.wikipedia.org/wiki/Is-a -- Steve _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
