Making (CLASS-OF <class>) be EQ to <class>

[Jon L White <jonl@lucid.com>]

Yea, there were numerous thorny issues connected to that one line of
code -- (change-class my-std-class my-std-class).  Here's a high-order,
three-line summary of each one:


1. When CHANGE-CLASS is applied to a class object, shouldn't it also call
   MAKE-INSTANCES-OBSOLETE on it?  [PCL mail from some time ago said yes.]
   Should this be as a :BEFORE method specialized to class CLASS?


2. If there are methods defined on function FOO at classes respectively
   <C1, C2 ...>, then how can one temporary override the effective method
   at that point, and cause it to defer to the next most specific one?


3. Have we adequately enumerated in a single place the kinds of system
   definitions that user code can redefine without suffering  "undefined 
   consequences"; e.g., are SETF function names and methods covered?


I'm especially interested in  what Symbolics does for point 1.


-- JonL --