March 2014 update

Task/Polymorphic-copy/Objective-C/polymorphic-copy.m

@@ -1,5 +1,4 @@
 @interface T : NSObject
-{ }
 - (void)identify;
 @end
 
@@ -17,7 +16,6 @@
 @end
 
 @interface S : T
-{ }
 @end
 
 @implementation S
@@ -29,11 +27,12 @@
 
 int main()
 {
-    T *original = [[S alloc] init];
-    T *another = [original copy];
-    [another identify]; // logs "I am an S"
+    @autoreleasepool {
 
-    [another release]; // like "alloc", the object returned by "copy" is "owned" by the caller, so we are responsible for releasing it
-    [original release];
+        T *original = [[S alloc] init];
+        T *another = [original copy];
+        [another identify]; // logs "I am an S"
+
+    }
     return 0;
 }

Task/Polymorphic-copy/Racket/polymorphic-copy-2.rkt

@@ -1,16 +1,19 @@
-;#lang racket
+#lang racket/base
 
-(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 (copy-struct str)
+  (define-values (str-struct-info _) (struct-info str))
+  (define str-maker (struct-type-make-constructor str-struct-info))
+  (apply str-maker (cdr (vector->list (struct->vector str)))))
 
-(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))))
+(struct point (x y) #:transparent)
+(struct point/color point (color) #:transparent)
+
+(let* ([original (point 0 0)]
+       [copied (copy-struct original)])
+  (displayln copied)
+  (displayln (eq? original copied)))
+
+(let* ([original (point/color 0 0 'black)]
+       [copied (copy-struct original)])
+  (displayln copied)
+  (displayln (eq? original copied)))

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))))