Re: New Specializers For CLOS

[kempf%hplabsz@hplabs.HP.COM]

> Proposal:
> Add a specializer form
>   (metaclass <class>)
> A method with such a specializer would be applicable if the metaclass of the
> object bound to the argument is of type specified by <class>.  


> Proposal: 
> Add a specializer
>     (subclass <class>)
> A method with a subclass specializer on an argument is applicable if the
> argument is of type <class> and is a subtype of the given class.

The outlined problems are largely in Chapter 3 and the suggested
solution will impact Chapters 1 & 2 as well. It might be better to
look for a solution which does not impact Chapters 1 & 2, to avoid
having to retrofit the changes.

Since one of the characteristics of these new specializers outlined in the 
proposal was that all methods on a generic function must 
agree on these new specializers (i.e. either have them or the regular set,
but not both), a new class of generic function is suggested
and, with it, perhaps a set of associated macros 
(DEFINE-METACLASS-METHOD ?) for conveniently defining the methods.

		jak