Class Delegation

Introduction#

A Kotlin class may implement an interface by delegating its methods and properties to another object that implements that interface. This provides a way to compose behavior using association rather than inheritance.

Delegate a method to another class

interface Foo {
    fun example()
}

class Bar {
    fun example() {
        println("Hello, world!")
    }
}

class Baz(b : Bar) : Foo by b

Baz(Bar()).example()

The example prints Hello, world!