[Python-Dev] type categories

[Guido van Rossum]

> Not really.  I can see how an interface can claim that a particular
> method exists, but not how it can claim that the method implements a
> function that is antisymmetric and transitive.

That's done in the docs, usually.  Zope even has the notion of a
"marker" interface -- an interface that says "this object has property
such-and-such" but which does not assert any methods or attributes.

--Guido van Rossum (home page: http://www.python.org/~guido/)