IDL interfaces

[Kragen Sitaker]

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.  :)