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From: ekrell@ucla-cs.UUCP
Newsgroups: net.lang,net.lang.st80
Subject: Re: Definition of Buzzwords: "Object-Oriented"
Message-ID: <3540@ucla-cs.ARPA>
Date: Wed, 30-Jan-85 00:13:36 EST
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Posted: Wed Jan 30 00:13:36 1985
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> >< 
> >   I read this somewhere: a procedure-oriented language represents the
> > behavior of a program by describing the effect of applying procedures
> > to different kinds of arguments (here procedures being a broad term
> > including assignments, arithmetic operators, etc).
> >   An object-oriented language does it by describing the effect of applying
> > different procedures (methods) to a specific object.
> > 
> 
> The definition is lacking two important things:  the definition of 'arguments'
> and the definition of 'objects'.  After all, an argument could, in some
> contexts be considered an object.

  I've read several definitions of what people think is object-orientation
and I think that most of them confuse it with ADTs (Abstract Data Types),
which are "objects" in the sense that they represent physical or abstract
objects such as a person or a stack, where the specification of the operations
on these objects  is separated from their implementation.
  This is nice (Information Hiding principle, etc) but that doesn't make
a language object-oriented. Ada and Modula-2 have all these goodies but
that doesn't make them object-oriented languages. I think people who know
SMALLTALK would agree with me.
  It is true that there's an analogy in applying a method to an object
and an operation to an ADT, but the way an expression "f(x)" would be
evaluated in a object-oriented language is "look at the type of object x
is; find a method called f defined for that object and apply it to x".
In a procedure-oriented language it would be "look at the definition of f
and apply f to x".
  It's clear, then, that an object-oriented language has overloading since
you could have methods with the same name for different objects. However,
the presence of overloading in a language (like ADA) doesn't mean it is
object-oriented...
-- 
    Eduardo Krell               UCLA Computer Science Department
    ekrell@ucla-locus.arpa      ..!{sdcrdcf,ihnp4,trwspp,ucbvax}!ucla-cs!ekrell