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Method-lambda and apply-method-lambda
- To: Commonfirstname.lastname@example.org
- Subject: Method-lambda and apply-method-lambda
- From: Patrick H Dussud <DUSSUD@Jenner.csc.ti.com>
- Date: Fri, 25 Mar 88 14:38:09 CST
I don't think that method-lambda, as describe in 88-003 is good enough. It
captures the contract between a class of generic functions and a class of methods,
so it should be metaclass driven. You can imagine several contracts on a single
I propose the following:
Make-method-function is a generic function.
make-method-function GENERIC-FUNCTION QUALIFIERS SPECIALIZERS LAMBDA-FORM &optional MACROEXPAND-ENVIRONMENT
Generic-function is the generic-function object. Note that it can be gotten at
compile-file time and is not expected to change incompatibly between
compile-file time and load time.
QUALIFIERS, SPECIALIZERS, LAMBDA-FORM are the "natural" arguments
MACROEXPAND-ENVIRONMENT is necessary in order to capture the lexical context.
It default to the null macroexpand environment.
The generic function make-method-function returns a function suitable for the
function slot of a method. Its representation is implementation dependent.
The example given in 88-003 would be changed to:
(defun trace-gf (gf)
(let ((nargs (generic-function-required-arguments gf))
(lambda-list (generic-function-lambda-list gf))
(specializers (make-list nargs :initial-element (symbol-class 't)))
(function (compile () (make-method-function gf qualifiers specializers
(format *trace-output* "~&Hi there.")
I am not sure that compile should or would work on the result of
make-method-function. This must be decided.
(defmethod (setf foo) :before ((x c1) y &rest z) (do-foo ...))
would expand into
(let ((gf (ensure-generic-function '(setf foo))))
(add-named-method gf '(:before)
'((x c1) y &rest z)
(make-method-function gf '(:before) '(c1 t)
'(lambda (x y &rest z) (do-foo ...))) environment))
apply-method-lambda must be changed for the same reasons.
I propose the following:
apply-method METHOD NEXT-METHOD-LIST &rest ARGUMENTS [ generic function]
apply-method is discriminated on METHOD.
METHOD is the method that needs to be invoked.
NEXT-METHOD-LIST is the list of all the methods that can be invoked by calling
ARGUMENTS are the "external" arguments to the method. The last one should be a
list of remaining arguments.
Implementations are free to optimize this to internal function calling primitives.