What is the Scala equivalent to a Java builder pattern?

Question

In the work that I do on a day to day in Java, I use builders quite a lot for fluent interfaces, e.g.: new PizzaBuilder(Size.Large).onTopOf(Base.Cheesy).with(Ingredien

Answer 1

It's the same exact pattern. Scala allows for mutation and side effects. That said, if you'd like to be more of a purest, have each method return a new instance of the object that you're constructing with the element(s) changed. You could even put the functions within the Object of a class so that there's a higher level of separation within your code.

class Pizza(size:SizeType, layers:List[Layers], toppings:List[Toppings]){
    def Pizza(size:SizeType) = this(size, List[Layers](), List[Toppings]())

object Pizza{
    def onTopOf( layer:Layer ) = new Pizza(size, layers :+ layer, toppings)
    def withTopping( topping:Topping ) = new Pizza(size, layers, toppings :+ topping)
}

so that your code might look like

val myPizza = new Pizza(Large) onTopOf(MarinaraSauce) onTopOf(Cheese) withTopping(Ham) withTopping(Pineapple)

(Note: I've probably screwed up some syntax here.)