On "thinnings":
> > In particular, more powerful interface variants often
> > want to return capabilities to less powerful interface variants, and you'ld
> > like to be able to type check that fact. It helps to know that the two
> > objects are really the same.
> >
> > I have not yet encountered an IDL input language that makes the expression
> > of this natural.
>
> how about introducing a new keyword or two:
The "thins" relationship is the inverse of the "extends" or "inherits from" relationship. The more powerful interface is simply a subclass of the less powerful interface.
Typically, statically-typed OO systems provide a way to get the subclass interface given the superclass interface to an object of a subclass. At least, C++ and Java do. I don't know about Eiffel. We don't want this feature.
-- <kragen@pobox.com> Kragen Sitaker <http://www.pobox.com/~kragen/> The Internet stock bubble didn't burst on 1999-11-08. Hurrah! <URL:http://www.pobox.com/~kragen/bubble.html> The power didn't go out on 2000-01-01 either. :)