Mastering High Performance with Kotlin

Class delegation

Let's rewrite the CalculatorMachine class in Kotlin:

class CalculatorMachine(private val delegate: Calculator): Calculator by delegate

That's it. Now you can use the CalculatorMachine class written in Kotlin similarly to the version written in Java:

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

You can see that the compiler generates the same bytecode for the Kotlin version of the CalculatorMachine class as for the Java version:

public final class delegation/kotlin/CalculatorMachine implements delegation/Calculator  {        private final Ldelegation/Calculator; delegate        public <init>(Ldelegation/Calculator;)V    @Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0    L0    ALOAD 1    LDC "delegate"    INVOKESTATIC ...