[Python-Dev] type categories

Andrew Koenig ark@research.att.com
Wed, 14 Aug 2002 17:55:47 -0400 (EDT)

>> However, now that you bring it up... One difference I see between
>> interfaces and categories is that I can imagine categories carrying
>> semantic information to the human reader of the code that is not
>> actually expressed in the category itself.  As a simple example,
>> I can imagine a PartialOrdering category that I might like as part
>> of the specification for an argument to a sort function.

Martijn> But isn't that exactly what interfaces are?

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.