Path: utzoo!attcan!telly!lethe!torsqnt!jarvis.csri.toronto.edu!mailrus!ames!uhccux!munnari.oz.au!cs.mu.oz.au!ok
From: ok@cs.mu.oz.au (Richard O'Keefe)
Newsgroups: comp.lang.c++
Subject: Re: OO terminology (Was: OO Design books)
Keywords: OOP, books
Message-ID: <2166@munnari.oz.au>
Date: 22 Sep 89 12:44:13 GMT
References: <583@calmasd.Prime.COM> <4557@orca.WV.TEK.COM> <1333@tukki.jyu.fi> <1989Sep21.185448.13515@oresoft.uu.net>
Sender: news@cs.mu.oz.au
Lines: 17

In article <1989Sep21.185448.13515@oresoft.uu.net>, dan@oresoft.uu.net (Daniel Elbaum) writes:
> 'super-' and 'sub-' class terminology can introduce confusion.
> If X is a a base class of Y, then a Y is an X but not vice-versa,
> and so X is the more general of the two.

Which is to say that the set of Xs is a SUPERset of the set of Ys.
Which is to say that "X is a superclass of Y" goes in exactly the
right direction.

> On the other hand, Y is a superset of X;
No, the set of Ys is a *SUB*set of the set of Xs.

> The 'base' and 'derived' terms are unambiguous and adequate.
In C++ this may well be so.  In general, it is possible to derive
more general structures from more specific ones by ``forgetting''
unwanted parts, so in other languages ``derived'' may not be so
suggestive.  And the context was terminology *across* languages.