Case classes, pattern matching and varargs

Question

Let\'s say I have such class hierarchy:

abstract class Expr
case class Var(name: String) extends Expr
case class ExpList(listExp: List[Expr]) extends Expr
         


        

Answer 1

You can have both constructors:

case class ExpList(listExp: List[Expr]) extends Expr
object ExpList {
  def apply(listExp: Expr*) = new ExpList(listExp.toList)
}

//now you can do
ExpList(List(Var("foo"), Var("bar")))
//or
ExpList(Var("foo"), Var("bar"))

Variadic arguments are converted to a mutable.WrappedArray, so to keep in line with the convention of case classes being immutable, you should use a list as the actual value.