CLOS question

[Cyphers@JASPER.SCRC.Symbolics.COM (Scott Cyphers)]

    Date: Tue, 7 May 1991 23:29 EDT
    From: KMP@STONY-BROOK.SCRC.Symbolics.COM (Kent M Pitman)

    Note well that according to this, existing instances (and, in fact, the
    class object itself) are not changed.  The instances and the class will be 
    removed by the  garbage collector if there are no more pointers to it.

    In practice, I don't know how likely it is that there will be no
    pointers, given that the class system itself probably still has pointers
    in order to implement inheritance.  But in any case, except that the old
    class and instances may still be taking up storage, the program-visible
    effect of doing this SETF should be equivalent to what you're asking for.

CLOS won't maintain pointers to any of your instances.

The class object will never go away in any system that supports the
metaobject generic function CLASS-DIRECT-SUBCLASSES.  (I know Symbolics
and Lucid support this).