Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!odi!dlw
From: dlw@odi.com (Dan Weinreb)
Newsgroups: comp.object
Subject: Re: Examples of Multiple Inheritance?
Message-ID: <1990Dec14.213203.14172@odi.com>
Date: 14 Dec 90 21:32:03 GMT
References: <841@echbull.bull.fr> <18090@neptune.inf.ethz.ch> <1990Dec13.035418.28040@Neon.Stanford.EDU> <47353@apple.Apple.COM>
Reply-To: dlw@odi.com
Organization: Object Design, Inc.
Lines: 18
In-Reply-To: lins@Apple.COM's message of 13 Dec 90 21:07:15 GMT

In article <47353@apple.Apple.COM> lins@Apple.COM (Chuck Lins) writes:

   >If you're concerned about space overheads of MI, other implementations
   >of MI than the one in C++ 2.0+ have low space overheads, comparable to
   >pre-MI C++ implementations (i.e. a word or two extra per object).

   Could you provide some examples or references to papers describing such
   implementations? For some of us this (oo research) is a part-time endeavor
   and we don't always have the time to read every single paper. (Our limits,
   not yours.) Thanks in advance.

The Symbolics CLOS implementation uses one word for each instance
variable, plus one word of overhead, no matter how much multiple
inheritance is being used.  I think that it is described in papers
that have been published in OOPSLA.  I believe that the portable
PCL implementation also has the same property (in fact, I strong
suspect that every single extant implementation of CLOS has this
property).