How do you define "object-oriented"?

Alejandro F. Reimondo aleReimondo at
Fri Apr 26 23:52:52 UTC 2002

Hi Dan, Jecel,

> > In my opinion, Object-orientation is: Objects
> > communicating through message passing.
> That sounds good.

That sounds good for me, but as a definition in our current "state of the
art" in Object Technology.
I think that if we find another mechanism (and medium) to replace message
sending in the future, the systems will be also object systems because they
are products of applying reductionism.

(Imagine) we can use machines where objects are "in contact" and diffusion
of fluids replace message passing... most of our "pure" Object Techniques
will be applicable.
Yes, we can talk on messages but at a high level, because diffusion in
liquids are fuzzy and messages can not be focused only on anObject and a
message can be altered while sent (like symbols and memes jumping between
mind to mind in a society).


----- Original Message -----
From: "Jecel Assumpcao Jr" <jecel at>
To: <squeak-dev at>
Sent: Friday, April 26, 2002 3:58 PM
Subject: Re: How do you define "object-oriented"?

> On Friday 26 April 2002 20:33, Dan Rozenfarb wrote:
> > > A language is object-oriented if it supports
> > > 1.  Encapsulation
> > > 2.  Inheritance
> > > 3.  Polymorphism
> >
> > Self hasn't Inheritance, at least Class Inheritance
> > (the one implied in this Wegner's definition), but
> > delegation.  And I consider it VERY object oriented.
> Wegner put (at least in his original Byte article) languages without
> classes in a separate "object based" category. But my opinion is the
> same as yours. In addition, I don't see any practical difference
> between "inheritance" and "delegation" even though I have read many
> papers about the subject.
> Smalltalk-72 and -74 didn't have inheritance, and neither did Kevo. I
> don't know about Simula 67.
> But I prefer not to fight for any particular meaning of "OO" (having
> learned my lesson in the "hacker" wars). Whatever Alan Kay meant with
> this term, people extended it to include Simula 67 (since he admitted
> having been inspired by it) and C++ is very much in the spirit of that
> old language. And if that is OO, then how could I argue that Java or
> Python aren't?
> > In my opinion, Object-orientation is: Objects
> > communicating through message passing.
> That sounds good.
> > [No compile-TIME, No edit-TIME, No NON-OBJECTs, No classes]
> > With this definition, Smalltalk is not *pure* OO.
> Because of the classes? See "Smalltalk with Examplars" or CoDA for
> Smalltalks with classless objects.
> Wilf R. LaLonde, Dave A. Thomas, John R. Pugh:
> "An Exemplar Based Smalltalk". In [OOPSLA 86], pp. 322-330.
> -- Jecel

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