Mastering Kotlin

Adding sodas

Let's start by adding support for adding a soda to our order:

1. To do this, we'll define Soda as a sealed class with several options to choose from:

sealed class Soda(name: String) : Item(name)object Coke : Soda("Coke")object Sprite : Soda("Sprite")object Dr_Pepper : Soda("Dr Pepper")

2. With our Soda class in place, we can add a soda to our order by accessing Order.items directly:

val order = order {    this.items[Coke] = this.items.getOrDefault(Coke, 0) + 1}

This works, but is verbose and requires direct interaction with the underlying data structure. Let's improve this by making the syntax more natural and by hiding the data structure.

There are a couple of ways in which we can do this, as follows:

1. First, let's refactor the previous ...