Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 UW 5/3/83; site uw-june
Path: utzoo!watmath!clyde!burl!ulysses!mhuxj!houxm!vax135!cornell!uw-beaver!uw-june!trow
From: trow@uw-june (Jay Trow)
Newsgroups: net.lang.st80
Subject: Re: instance variable question
Message-ID: <1847@uw-june>
Date: Mon, 8-Oct-84 20:40:13 EDT
Article-I.D.: uw-june.1847
Posted: Mon Oct  8 20:40:13 1984
Date-Received: Tue, 9-Oct-84 04:09:59 EDT
References: <15992@arizona.UUCP>
Reply-To: Krasner@Xerox.arpa, Smalltalk80Interest^@Xerox.arpa
Organization: U of Washington Computer Science
Lines: 28


Forwarded from Smalltalk80Interest^@Xerox.arpa

----------------------------------------------------------------

Date: Mon, 8 Oct 84 8:52:48 PDT
From: krasner@xerox.arpa
Subject: Re: instance variable question

Restricting classes to use only the instance variables defined in them
and not in their superclass will result in making inheritance almost useless.
Inheritance for us has proven to be significantly more powerful than the
ability to change class definitions.  So given the trade-off between
restricting the power of inheritance and longer execution time for re-defining
classes, I would recommend that you opt for the latter, as described in
Kim McCall's message.

The entire Smalltalk-80 system source code is part of the ($400 for
universities) license package.  Reading the sources would help you answer
some of these types of questions.  You do not necessarily have to have a
running system to browse the code--at least one of our licensees, for example,
was able in about a week to write a reasonably powerful Unix tool to browse
the code before their system was widely available.  I recommend you try to
get a license for U. of Arizona; let me know if you need more details on how.

Glenn Krasner

----------------------------------------------------------------