Delegation in Kotlin

Classes.kt

interface PetAction {
    fun eat()
}

interface PetColor {
    val color: String
}

object YellowColor : PetColor {
    override val color = "yellow"
}

class PrintingPetAction(val food: String) : PetAction {
    override fun eat() {
        println(food)
    }
}

class Cat(petColor: PetColor = YellowColor) :
    PetAction by PrintingPetAction("eats a lot of fish"),
    PetColor by petColor

fun delegate() {
    val kittyCat = Cat()
    println("Pet has color ${kittyCat.color}") 
    kittyCat.eat() 
}

fun main(args: Array<String>) {
    delegate()
}

// => Pet has color yellow
// => eats a lot of fish