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From: fairley@wanginst.UUCP (Dr. Richard Fairley)
Newsgroups: net.lang,net.lang.st80
Subject: Re: Definition of Buzzwords: "Object-Oriented"
Message-ID: <163@wanginst.UUCP>
Date: Mon, 28-Jan-85 17:50:15 EST
Article-I.D.: wanginst.163
Posted: Mon Jan 28 17:50:15 1985
Date-Received: Wed, 30-Jan-85 05:24:18 EST
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> I have recently been involved in some discussions in which the topic
> of so-called "object-oriented" languages and programming techniques
> has been explored. Despite the fact that "everybody knows" that
> Smalltalk-80 is "object-oriented" and "everybody knows" (or pretends
> that they do) what "object-oriented programming" is, this same
> group of "everybody"s is having a hard time coming up with a rigorous
> definition of those terms which goes beyond one of the two following:
> 
> 1) The term is self-explanatory: the orientation of the language/program
>    is towards the "object". This causes the discussion to move in
>    the direction of defining an "object", and how exactly the language
>    or program is oriented in that direction.
> 
> 2) The term is defined by example: if somebody says a language is "object-
>    oriented" and most people agree, then the language is object-oriented
>    (the "science fiction" definition approach - "science fiction" is what
>    "science fiction authors" write, "science fiction editors" buy, and
>    "science fiction fans" read).
> 
> Neither of these approaches makes anybody particularly happy. Nobody's
> been able to find an accepted definition in the literature, either.
> So, the question is:
> 
> Is there a definition of the term "object-oriented" which is both descriptive
> of all current uses of that term and accepted by all who currently use it?
> If not, can such a definition be constructed?
> 
> I would be interested in hearing from anybody who has any ideas relating
> to this topic.
> 
>                                         Bill Laubenheimer
> ----------------------------------------UC-Berkeley Computer Science
>      ...Killjoy went that-a-way--->     ucbvax!wildbill

In my view, object-oriented means data abstraction PLUS inheritance and
dynamic binding; although most data abstraction languages use strong type 
checking, which is inconsistent with dynamic binding.  By data abstraction, 
I mean separation of specification from implementation, information hiding, 
and state retention within the object.  

The term object-oriented has been appropriated by different disciplines: 
database, architecture, operating systems, and programming languages all use 
the term with different meanings.  The term is especially confused within the
programming field because Grady Booch and the Ada crowd use the term for
what most people refer to as data abstraction; i.e., information hiding
with state retention and strong type checking.

The easiest way to distinguish object-orientation from data abstraction is
to say it's what Smalltalk does that Ada does not.  I think you will find that 
the Smalltalk people at Xerox PARC have the historical edge on use of the term.


				Dick Fairley
				decvax!wanginst!fairley