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Re: Class redefinition and class-changed.

     Date: 24 Jul 87 08:48 PDT
     From: Danny Bobrow <Bobrow.pa@xerox.com>
     Subject: Re: Class redefinition and class-changed.
     It doesn't have to guess.  If the class changed method is defined before
     any any method is called on an obsolete instance, it will be used.
     Otherwise not.  Hence users should define such class-changed methods
     immediately (soon) after redefining the class. 
In multiprocessing or interruptible environment, immediately is a weak
concept at best.  You might get in a race condition with another
computation unit that touches instances.  Furthermore, you can't prove
that some instances haven't been updated before you define the
changed-class method. How do you propose to solve this?