我试图在Common Lisp中对多方法进行"重载调用".这是案例的简化纲要:
(defclass foo ()
((slotty :accessor slotty :initarg :slotty)))
(defclass bar ()
((slotty :accessor slotty :initarg :slotty)))
(defparameter *foo* (make-instance 'foo :slotty "defnoodle"))
(defparameter *bar* (make-instance 'bar :slotty "Chocolate"))
(defmethod contrived ((f foo) (b bar))
(format t "i pity the foo ~A, who has a bar ~A ~%" (slotty f) (slotty b)))
(contrived *foo* *bar*)
输出: i pity the foo defnoodle, who has a bar Chocolate
但是一旦我尝试定义下一个方法:
(defmethod contrived ((f foo))
(format t "i just pity the foo ~A …