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From: harrisr@CS.RPI.EDU (Richard Harris)
Newsgroups: comp.lang.clos
Subject: Creating metaclasses
Message-ID: <9105020128.AA28067@cs.rpi.edu>
Date: 2 May 91 01:28:07 GMT
Sender: welch@tut.cis.ohio-state.edu
Distribution: inet
Organization: CommonLoops
Lines: 22

Is it possible to achieve something with an effect equivalent
to the following forms in a portable way with the MOP?

(defclass my-object (standard-object)
  ((file))
  (:metaclass my-class))

(defclass my-class (standard-class my-object)
  ((my-class-info))
  (:metaclass my-class))

The following excerpt from Chapter 6 seems to suggest that
what I want is impossible.

   Since metaobject classes may not be redefined, no behavior is specified for
   the result of calls to {\bf update-instance-for-redefined-class} on class
   metaobjects.  Since the class of class metaobjects may not be changed, no
   behavior is specified for the result of calls to {\bf
   update-instance-for-different-class} on class metaobjects.

----
  Richard Harris