Building big, immutable objects without using constructors having long parameter lists

Question

I have some big (more than 3 fields) objects that can and should be immutable. Every time I run into that case I tend to create constructor abominations with long parameter

Answer 1

In Scala 2.8, you could use named and default parameters as well as the copy method on a case class. Here's some example code:

case class Person(name: String, age: Int, children: List[Person] = List()) {
  def addChild(p: Person) = copy(children = p :: this.children)
}

val parent = Person(name = "Bob", age = 55)
  .addChild(Person("Lisa", 23))
  .addChild(Person("Peter", 16))