Mastering High Performance with Kotlin

Explicit delegation

Explicit delegation can be implemented by passing the delegate object to the delegating object. We can do this in any object-oriented language, such as Java. Let's create a Calculator interface:

public interface Calculator {    int performOperation(String operand);}

We'll also create a CalculatorBrain class that implements the Calculator interface:

public class CalculatorBrain implements Calculator {    public int performOperation(String operand) {        throw new IllegalStateException("Not implemented!");    }}

Now we'll implement a CalculatorMachine class. An instance of this class is a delegating object that delegates authority to an instance of Calculator, which is a delegate object. Let's create the CalculatorMachine class, which ...