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From: jwz@lucid.com (Jamie Zawinski)
Newsgroups: comp.lang.clos
Subject: CLOS/Flavors (was Re: Is CLOS Object-Oriented ???)
Message-ID: <JWZ.90Nov16173417@kolyma.lucid.com>
Date: 17 Nov 90 01:34:17 GMT
References: <1990Nov15.101847.26285@diku.dk> <3904@s3.ireq.hydro.qc.ca>
Sender: jwz@lucid.com
Organization: Lucid, Inc., Menlo Park, CA
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In-reply-to: gamin@ireq-robot.hydro.qc.ca's message of 15 Nov 90 22:12:34 GMT

In article <3904@s3.ireq.hydro.qc.ca> gamin@ireq-robot.hydro.qc.ca (Martin Boyer) wrote:

    Consider the classic
    
    (send square :draw-yourself)
    
    and let's say we want to add some functionality by allowing an extra
    argument to indicate where this square should be drawn:
    
    (send square :draw-yourself :on-screen)
    (send square :draw-yourself :on-printer)
    
    In Flavors, one would have to re-write the draw-yourself method to
    discriminate on the second argument, because the procedure depends on
    it.  But wait!  isn't that what "send" was supposed to do in the first
    place, discriminate on the first argument to find out which method to
    use?  We now need 'draw-yourself' methods specialized on more than one
    argument, the object and the medium (as if, in this case, the medium
    IS the message :-)).

BZZZZZT!  Thank you for playing.

(defmethod (square :draw-yourself :case :on-screen) () ... )
(defmethod (square :draw-yourself :case :on-printer) () ... )

  -- Jamie "you can supplant old-Flavors when you pry it from my 
     cold dead fingers" Zawinski