September 2017 Update

Task/Polymorphic-copy/Kotlin/polymorphic-copy.kotlin

@@ -0,0 +1,21 @@
+// version 1.1.2
+
+open class Animal(val name: String, var age: Int) {
+    open fun copy() = Animal(name, age)
+
+    override fun toString() = "Name: $name, Age: $age"
+}
+
+class Dog(name: String, age: Int, val breed: String) : Animal(name, age) {
+    override fun copy() = Dog(name, age, breed)
+
+    override fun toString() = super.toString() + ", Breed: $breed"
+}
+
+fun main(args: Array<String>) {
+    val a: Animal = Dog("Rover", 3, "Terrier")
+    val b: Animal = a.copy()  // calls Dog.copy() because runtime type of 'a' is Dog
+    println("Dog 'a' = $a")   // implicitly calls Dog.toString()
+    println("Dog 'b' = $b")   // ditto
+    println("Dog 'a' is ${if (a === b) "" else "not"} the same object as Dog 'b'")
+}