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From: pcb@cacs.usl.edu (Peter C. Bahrs)
Newsgroups: comp.object
Subject: Re: Re: How would yo model this situation?
Message-ID: <17486@rouge.usl.edu>
Date: 28 Oct 90 18:29:27 GMT
Sender: anon@rouge.usl.edu
Organization: The Center for Advanced Computer Studies, USL
Lines: 38

> I wrote... Responses...

Well I have seen a lot of interesting responses on the net and through
email.  I wish news allowed graphical postings so I could send a
picture of the solutions.

But,
  what happens to the rope object?  It breaks in two, but each
piece has most of the characteristics of the original piece (except
things like someone on the other end, length, ...).
  The two people can still access their respective rope objects.
  Is this still one rope object that now mangages 2 pieces instead
  of one?  (this is simple to do)
  Or should the rope object mutate?  i.e. break into two distinct
   objects, each with a unique identity and local state.
  (Is there an OO term for this?)
  If this is the case, the old rope object must tell each person...
    "...here, this is the new name of your rope object..." and then
  the rope object must destroy itself.  Then the person object cannot
  hard code a declartion to a rope object but keep an association or
   delegation list somewhere.

             So,      | rope |   mutates, then disappears
                        /  \
                    rope2a  rope2b
  
  Any comments?  I suspect that all of this can be modeled in the
  behaviors of the objects in languages like C++ and Smalltalk.  But
  are there systems that provide mutation?

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| Peter C. Bahrs                                                         |
| The USL-NASA Project                                                   |
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