Just another update

Task/Polymorphic-copy/Ada/polymorphic-copy.ada

@@ -3,6 +3,7 @@ with Ada.Text_IO;  use Ada.Text_IO;
 procedure Test_Polymorphic_Copy is
    package Base is
       type T is tagged null record;
+      type T_ptr is access all T'Class;
       function Name (X : T) return String;
    end Base;
    use Base;
@@ -21,6 +22,12 @@ procedure Test_Polymorphic_Copy is
       Put_Line ("Copied " & Duplicate.Name); -- Check the copy
    end Copier;
 
+      -- The function knows nothing about S and creates a copy on the heap
+   function Clone (X : T'Class) return T_ptr is
+   begin
+      return new T'Class(X);
+   end Copier;
+
    package Derived is
       type S is new T with null record;
       overriding function Name (X : S) return String;
@@ -36,7 +43,11 @@ procedure Test_Polymorphic_Copy is
 
    Object_1 : T;
    Object_2 : S;
+   Object_3 : T_ptr := Clone(T);
+   Object_4 : T_ptr := Clone(S);
 begin
    Copier (Object_1);
    Copier (Object_2);
+   Put_Line ("Cloned " & Object_3.all.Name);
+   Put_Line ("Cloned " & Object_4.all.Name);
 end Test_Polymorphic_Copy;

Task/Polymorphic-copy/D/polymorphic-copy-2.d

@@ -20,7 +20,7 @@ class S : T {
     }
 
     override string toString() {
-        return "I'm the instance of S p: " ~ cast(string)str;
+        return "I'm the instance of S p: " ~ str.idup;
     }
 
     override T duplicate() { return new S(this); }
@@ -41,6 +41,6 @@ void main () {
     T copy = orig.duplicate();
     orig.custom('Y');
 
-    writeln(orig);
-    writeln(copy); // Should have 'X' at the beginning.
+    orig.writeln;
+    copy.writeln; // Should have 'X' at the beginning.
 }

Task/Polymorphic-copy/Groovy/polymorphic-copy-1.groovy

@@ -0,0 +1,14 @@
+class T implements Cloneable {
+    String property
+    String name() { 'T' }
+    T copy() {
+        try { super.clone() }
+        catch(CloneNotSupportedException e) { null }
+    }
+    @Override
+    boolean equals(that) { this.name() == that?.name() && this.property == that?.property }
+}
+
+class S extends T {
+    @Override String name() { 'S' }
+}

Task/Polymorphic-copy/Groovy/polymorphic-copy-2.groovy

@@ -0,0 +1,14 @@
+T obj1 = new T(property: 'whatever')
+S obj2 = new S(property: 'meh')
+
+def objA = obj1.copy()
+def objB = obj2.copy()
+
+assert objA.class == T
+assert objA == obj1 && ! objA.is(obj1) // same values, not same instance
+
+assert objB.class == S
+assert objB == obj2 && ! objB.is(obj2) // same values, not same instance
+
+println "objA:: name: ${objA.name()}, property: ${objA.property}"
+println "objB:: name: ${objB.name()}, property: ${objB.property}"