Hands-On Design Patterns with Kotlin

Switching sides

So, how do higher-order functions help us here?

First, we'll define a namespace for all our weapons. This is not mandatory, but helps to keep everything in check:

object Weapons {    // Functions we'll be there soon}

Then, instead of classes, each of our weapons will become a function:

val peashooter = fun(x: Int, y: Int, direction: Direction):             Projectile {        // Fly straight}val banana = fun(x: Int, y: Int, direction: Direction):     Projectile {        // Return when you hit screen border}val pomegranate = fun(x: Int, y: Int, direction: Direction):             Projectile {        // Explode when you hit first enemy}    

The most interesting part is our hero. It now holds two functions:

class OurHero {    // As before    var currentWeapon = Weapons.peashooter    val  ...