ex

pitfall/restructure/generic-interface-example.rkt

@@ -0,0 +1,20 @@
+#lang br
+(require data/collection racket/private/generic-methods)
+
+(define countable<%>
+  (interface* ()
+              ([(generic-property gen:countable)
+                (generic-method-table gen:countable
+                                      (define (length o)
+                                        (send o length)))])))
+
+
+(define c (class* object% (countable<%>)
+            (super-new)
+            (define/public (length) 42)))
+
+c
+
+(define o (make-object c))
+
+(length o)