Functional Kotlin

Class delegation

Class delegation is another interesting feature of Kotlin. How? Just think of the following situation.

You have an interface, I, and two classes, A and B. Both A and B implement I. In your code, you've an instance of A and you want to create an instance of B from that A.

In traditional inheritance, it is not directly possible; you have to write a bunch of nasty codes to achieve that, but class delegation is there to save you.

Go through the following code:

interface Person { fun printName() } class PersonImpl(val name:String):Person { override fun printName() { println(name) } } class User(val person:Person):Person by person { override fun printName() { println("Printing Name:") person.printName() } } fun main(args: Array<String>) ...