> (defclass bar (foo) ((d :accessor foo-d :initarg :d :initform 4))) #<STANDARD-CLASS BAR> > (setq bar1 (make-instance 'bar :a 1 :b 2)) #<BAR @ #x203c6b12> > (foo-a bar1) 1 > (foo-b bar1) 2 > (foo-c bar1) 3 > (foo-d bar1) 4 > (defmethod foo-method ((x foo)) (slot-value x 'a)) #<STANDARD-METHOD FOO-METHOD (FOO) 42720573> > (foo-method foo1) UNO > (foo-method bar1) 1 > (defmethod foo-method ((x bar)) (slot-value x 'd)) #<STANDARD-METHOD FOO-METHOD (BAR)> > (foo-method bar1) 4barクラスはfooクラスを親として,そのクラスの性質 を継承します.