8.6.1


(defclass thing ()

((weight :initform (0 kg)

:accessor weightof

:initarg :weight)))

(defclass animal (thing)

((specie :accessor specieof

:initarg :spec)

(sex :accessor sexof

:initform m

:initarg :sex)))

(defclass possession (thing)

((owner :accessor ownerof

:initform nnn)

(cost :accessor costof

:initform (0 bucks)

:initarg :cost))

)

(defclass person (animal)

((specie :initform human)

(name :initarg :thename

:accessor nameof)))

(defclass pet (animal possession)

((nick :initarg :thenick

:accessor nickof)

(specie :initform cat)))

(defmethod act :before ((p pet))

(print "Cat mews"))

(defmethod act :after ((p pet))

(print "Cat turns"))

(defmethod act :around ((p pet))

(progn (print "You have a cat") (call-next-method)))

(defmethod act ((p animal))

(progn (print "Animal is close to you") (call-next-method)))

(defmethod act :before ((p animal))

(print "You see an animal"))

(defmethod act :after ((p animal))

(print "You send the animal off"))

(defmethod act :around ((p animal))

(progn (print "You dont like wild animals") (call-next-method)))

(defmethod act ((p possession))

(progn (print "You test your property") (call-next-method)))

(defmethod act :before ((p possession))

(print "You see your property"))

(defmethod act :after ((p possession))

(print "You are pleased by your property"))

(defmethod act :around ((p possession))

(progn (print "You admire your property

if it is in good state") (call-next-method)))

(defmethod act ((p thing))

(print "You take the thing"))

(defmethod act :before ((p thing))

(print "You see something"))

(defmethod act :after ((p thing))

(print "You identified this thing"))

(defmethod act :around ((p thing))

(progn (print "You are not interested

in strange things") (call-next-method)))

(act (make-instance pet :thenick "Viola" :cost (25 kop)))