tasks a-s

Task/Polymorphism/Common-Lisp/polymorphism.lisp

@@ -0,0 +1,23 @@
+(defclass point ()
+  ((x :initarg :x :initform 0 :accessor x)
+   (y :initarg :y :initform 0 :accessor y)))
+
+(defclass circle (point)
+  ((radius :initarg :radius :initform 0 :accessor radius)))
+
+(defgeneric shallow-copy (object))
+(defmethod shallow-copy ((p point))
+  (make-instance 'point :x (x p) :y (y p)))
+(defmethod shallow-copy ((c circle))
+  (make-instance 'circle :x (x c) :y (y c) :radius (radius c)))
+
+(defgeneric print-shape (shape))
+(defmethod print-shape ((p point))
+  (print 'point))
+(defmethod print-shape ((c circle))
+  (print 'circle))
+
+(let ((p (make-instance 'point :x 10))
+      (c (make-instance 'circle :radius 5)))
+  (print-shape p)
+  (print-shape c))