Re: Nonstandard method combinations?

BTW, I've tried the code on LispWorks, SBCL, and Allegro, and only LispWorks does not lead to error after executing (upgrade-config-file 2). The error is "More than one method of type METHODS with the same specializers." Is there an error in my code?

Michal

On 2006-10-28 16:11:14 +0200, Michal Krupka <kokoml2@xxxxxxx> said:

(define-method-combination sort-and-cut ()
((methods positive-integer-qualifier-p))
(:arguments from)
(flet ((met-stage (met)
(first (method-qualifiers met))))
`(progn ,@(mapcar #'(lambda (method)
`(when (>= ,(met-stage method) ,from)
(call-method ,method)))
(stable-sort methods #'< :key #'met-stage))
nil)))
(defun positive-integer-qualifier-p (method-qualifiers)
(and (= (length method-qualifiers) 1)
(typep (first method-qualifiers) '(integer 0 *))))

(defgeneric upgrade-config-file (stage)
(:method-combination sort-and-cut))

(defmethod upgrade-config-file 0 (stage)
(print "Upgraded from version 0 to 1"))

(defmethod upgrade-config-file 1 (stage)
(print "Upgraded from version 1 to 2"))

(defmethod upgrade-config-file 2 (stage)
(print "Upgraded from version 2 to 3"))

(defmethod upgrade-config-file 3 (stage)
(print "Upgraded from version 3 to 4"))

(upgrade-config-file 2)


.