Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!samsung!brutus.cs.uiuc.edu!zweig
From: zweig@brutus.cs.uiuc.edu (Johnny Zweig)
Newsgroups: comp.object
Subject: Re: What is OOP? (not asking for intro. stuff)
Message-ID: <1990Feb12.204645.12441@brutus.cs.uiuc.edu>
Date: 12 Feb 90 20:46:45 GMT
References: <+B8|X-@rpi.edu>
Sender: news@brutus.cs.uiuc.edu
Reply-To: zweig@cs.uiuc.edu
Organization: U of Illinois, CS Dept., Systems Research Group
Lines: 26


I think it is important to distinguish Object-Oriented Programming in the
definitive sense from what O-O programmers do when they get to work every
day.  OOP means organizing software in a natural way that consists of objects
performing operations on one-another (as opposed to functions that operate
on more loosely-structured data).  This means that classes exist -- but does
not mean (IMHO) that you need class-hierarchies or types.  Consider a
delegation-based language:  everyone who delegates to object Foo can be
considered to be a member of a class (to wit: the class of all objects that
are similar enough that I make them all delegate to Foo).  I think you need
some notion of class to even be able to talk about an object-oriented
program -- if I have a bunch of objects, I need to be able to describe (at
least to another human; the code need not embody this knowledge) what _kind_
of object each one is, and what it's _for_.

I think class-hierarchies, inheritance and typing (ignore that last one all
you SmallTalkers) come pretty naturally once you commit yourself to making a
program that consists of objects.  It comes under the "what you do when you
get to work" part of it -- nobody would use an O-O language without some way
of reusing behavior (inheritance/delegation) if they were doing OOP and had
any way of getting away with using one that does (note the subtle Ada-bashing
in there).  The stuff people argue about ("tastes classy!" vs. "less typing!")
is really not part of "what OOP is" rather, it is part of "how I like to do
OOP".

-Johnny Distinction