Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!sdd.hp.com!hplabs!hplabsz!cook
From: cook@hplabsz.HPL.HP.COM (William Cook)
Newsgroups: comp.object
Subject: Re: The essence of objects...
Summary: Is anybody out there?
Keywords: oop, adt, bibliography
Message-ID: <5743@hplabsz.HPL.HP.COM>
Date: 7 Aug 90 18:17:49 GMT
References: <1280@media01.UUCP> <1964@runxtsa.runx.oz.au> <1288@media01.UUCP> <5666@hplabsz.HPL.HP.COM>
Organization: Hewlett-Packard Laboratories
Lines: 21


I was just wondering why nobody ever replies to my postings... its
been almost two weeks.  I know I didn't use any jargon
and my example was concrete, but can't you come up with something
to flame about?  Here, let me try again.  My point was that object-oriented
programming arises from a technical dichotomy in the organization of
the observers and constructors of a data abstraction.  Abstract data
types and objects (which I call procedural data abstractions)
are the result of these two alternatives.  Organization by `observer'
results in an abstract data type; organization by `constructor' results
in a object/class structure.  They *both*
model the "real world"; they *both* have `objects' and `operations';
finding the nouns and the verbs will help just as much in each case
(or be of as little help...).  The difference is how
things are organized, and this makes a big difference:  multiple
interacting implementations are easier in object-oriented programming,
while correctness proofs and optimizations are easier in abstract 
data types.  Shall I take silence for agreement?  I mean, isn't 
usenet the place to grind one's axes...

william cook@hplabs.hp.com