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> Date: Wed, 1 Mar 89 19:50 PST
> From: Gregor.pa@Xerox.COM
> > An error is signaled on an attempt to add a method on any built-in class.
> ... I think the first is just covered by one of the principles outlined in
> chapter 3.  ...

Yes.  I haven't gotten Chapter 3 assimilated into my thinking yet.

> > Adding a method on a class after ALLOCATE-INSTANCE has been called on the
> > class has undefined consequences. 
> {This} seems well intentioned but unreasonable.  For one thing, some
> implementations may call allocate-instance before defclass returns.  For
> another, it seems too painful to suggest that in order to define such a
> method you have to boot your lisp first.  If this is really the only way the
> rest of the proposal can hold together, I think we need to reconsider the
> proposal. 

I agree this is a serious weak point.  Clearly, something needs to be said here
about the problem of breaking existing data structures by redefining the
functions they were built with.  The restriction I wrote was intended mostly as
a place-holder while we try to come up with something better.