March 2014 update

Task/Polymorphic-copy/Racket/polymorphic-copy-3.rkt

@@ -0,0 +1,16 @@
+;#lang racket
+
+(define point%
+  (class object%
+    (super-new)
+    (init-field x y)
+    (define/public (clone) (new this% [x x] [y y]))
+    (define/public (to-list) (list this% x y))))
+
+(define point/color%
+  (class point%
+    (super-new)
+    (inherit-field x y)
+    (init-field color)
+    (define/override (clone) (new this% [x x] [y y] [color color]))
+    (define/override (to-list) (list this% x y color))))