Builder pattern (Design patterns in Scala)

abstract class Product

abstract class PizzaBuilder {
var dough: String
var sauce: String
var topping: String

def withDough(dough: String): PizzaBuilder
def withSauce(sauce: String): PizzaBuilder
def withTopping(topping: String): PizzaBuilder

def build: Product
}

class Pizza(builder: PizzaBuilder) extends Product {
val dough: String = builder.dough
val sauce: String = builder.sauce
val topping: String = builder.topping

override def toString: String = {
"Dough:" + dough + " Topping:" + topping + " Sauce:" + sauce
}
}

class Cook extends PizzaBuilder {
var dough: String = ""
var sauce: String = ""
var topping: String = ""

override def withDough(dough: String): PizzaBuilder = {
this.dough = dough
this
}

override def withSauce(sauce: String): PizzaBuilder = {
this.sauce = sauce
this
}

override def withTopping(topping: String): PizzaBuilder = {
this.topping = topping
this
}

override def build: Product = new Pizza(this)
}

object PizzaBuilderExample {
def main(args: Array[String]) = {
val hawaiianCook = new Cook().withDough("cross").withTopping("ham+pineapple").withSauce("mild")
val hawaiianPizza = hawaiianCook.build
println("Hawaiian Pizza:" + hawaiianPizza)
}
}

PizzaBuilderExample.main(Array())