[Zope] Are "Interfaces" anything more than a documentation mechanism

[Phil Glaser]

Hi Dieter,

> "Interfaces" are rarely used in Zope2 (there are a few exceptions, e.g.
> the "pluggable indexes" of the ZCatalog).
>
> But in Zope3, they will be fundamental for plugging components together...

Ok, but that begs the question: are Interfaces architecturally significant,
or is their utility retricted to providing a mechanism for documenting
classes?

I realized last night that my confusion about this was not only because of
the superficial resemblance between interfaces/components and C++ abstract
classes, but also because of COM: "interface," "Component," and the notion
of querying an interface are core concepts in the COM architecture. But,
again, unless I missed something, I did not see anything in the Interface
documentation that would lead me to believe that Interfaces in Zope are
anything more than a documentation mechanism.

Thanks for your help!

Regards,

Phil