Re: Continuing comments on Draft 11

[Gregor Kiczales <gregor@parc.xerox.com>]

   Date: 	Fri, 2 Nov 1990 13:32:00 PST
   From: Scott Cyphers <Cyphers@JASPER.SCRC.Symbolics.COM>

       Date: Fri, 2 Nov 1990 16:11 EST
       From:	Gregor Kiczales <Gregor@parc.xerox.COM>

       If the user wanted to define a new class of method that added a lexical
       function binding FOO around the body they would define a method like:

       (defmethod make-method-lambda ((gf standard-generic-function)
				      (method my-method-1)
				      lambda
				      environment)
	 (call-next-method gf
			   method
			   `(,(car lambda) ,(cadr lambda)
			      `(flet ((foo ..)) ,@(cddr lambda)))
			   environment))

   This would work (if you fixed the bug) just as well if you didn't say
   that make-method-lambda returned a function which took two arguments, so
   I don't see why you should be saying it.

       METHOD-FUNCTION, on a method, would return a function of two arguments
       (a list of args and a list of next methods).  This is important to have
       for things like user-built steppers.  The implementation-model would be
       that impls would call METHOD-FUNCTION, but, as usual, they don't have to
       call it if they know what they are going to get.  That is, there are no
       relevant meta-level incursions.

   If a function FUNCALL-METHOD-LAMBDA took arguments of a
   MAKE-METHOD-LAMBDA's first and second values, a list of next methods, a
   boolean of whether or not next methods were allowed, and the arguments
   to the function, I could write such a FUNCALL-METHOD-LAMBDA function.
   Is that good enough for a stepper?

I am not sure I understand either of your comments, but I have a
question that may clarify them for me.  Are you implicitly assuming that
any user methods on make-method lambda would call CALL-NEXT-METHOD as in
my example.  That is, are you assuming that the ultimate value returned
by MAKE-METHOD-LAMBDA would have been produced by an implementation
method?

If so, that would mean that I couldn't write call-next-method or
next-method-p for myself.

btw, I fixed the bug