Time for an 2014 update…

Task/Polymorphism/Groovy/polymorphism-1.groovy

@@ -0,0 +1,18 @@
+@Canonical
+@TupleConstructor(force = true)
+@ToString(includeNames = true)
+class Point {
+    Point(Point p) { x = p.x; y = p.y }
+    void print() { println toString() }
+    Number x
+    Number y
+}
+
+@Canonical
+@TupleConstructor(force = true)
+@ToString(includeNames = true, includeSuper = true)
+class Circle extends Point {
+    Circle(Circle c) { super(c); r = c.r }
+    void print() { println toString() }
+    Number r
+}

Task/Polymorphism/Groovy/polymorphism-2.groovy

@@ -0,0 +1,8 @@
+def p = new Point(x: 3, y: 4)
+def c = new Circle(x: 4, y: 3, r: 5)
+
+[(p): new Point(p), (c): new Circle(c)].each { v1, v2 ->
+    print "Verifying $v1 == "
+    v2.print()
+    assert v1 == v2
+}