Polymorphic copy: Difference between revisions

=={{header|Kotlin}}==

<lang scala>// 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'")

}</lang>

{{out}}

<pre>

Dog 'a' = Name: Rover, Age: 3, Breed: Terrier

Dog 'b' = Name: Rover, Age: 3, Breed: Terrier

Dog 'a' is not the same object as Dog 'b'

</pre>