[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: change to instance structure protocol

   Date: 	Fri, 30 Nov 1990 14:09:38 PST
   From: Jon L White <jonl@lucid.com>
   Comments: spoke too soon, but by how much?

   Now, regarding the quoted section of "Chap 3, draft 11" -- it isn't 
   clear to me just what it is trying to accomplish.  Does it imply that it
   is illegal to define an :AFTER method on ALLOCATE-INSTANCE specialized 
   to, say, FUNCALLABLE-STANDARD-CLASS?  If so, then I don't see the point 
   of it; but if not, then just what is it trying to say?

I thought I had answered this before, perhaps not.  Think of this as the
natural analog of the Lisp Symbol Redefinition issue.  It is trying to
make the method definition you propose illegal, and it is doing it
because that method is a "reserved word."  There are two problems with
letting users define methods like it:

 1) They could bash a system method.

 2) Two users could remove each other's methods; in this sense,
    defining a method like the one you propose is like programming
    with advice rather than metaobject programming.