Kotlin delegation classes:- Geniusofstudent

Delegation

Class Delegation

The Delegation pattern has proven to be a good alternative to implementation inheritance, and Kotlin supports it natively requiring zero boilerplate code. A class Derived can inherit from an interface Baseand delegate all of its public methods to a specified object:

interface Base {
    fun print()
}

class BaseImpl(val x: Int) : Base {
    override fun print() { print(x) }
}

class Derived(b: Base) : Base by b

fun main(args: Array<String>) {
    val b = BaseImpl(10)
    Derived(b).print() // prints 10
}

The by-clause in the supertype list forDerived indicates that b will be stored internally in objects of Derived and the compiler will generate all the methods of Base that forward to b.