Can't I define defaults if I define multiple overloaded constructors in Scala?

user_274627 0
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I've defined multiple constructors, with some default argument values in all of them. Looks correct (I can't see any ambiguity), but Scala (2.8) compiler complains:

multiple overloaded alternatives of constructor define default arguments

Does it mean that I can't define default values for overloaded constructors at all?

Let me illustrate the situation (primitivized, of course, but illustrative):


class A(subject : Double, factor : Int = 1, doItRight : Boolean = true) {

  def this (subject : Int, factor : Int = 1, doItRight : Boolean = true) = {
    this(subject.toDouble , factor, doItRight)
  }

  def this (subject : String, factor : Int = 1, doItRight : Boolean = true) = {
    this(subject.toDouble , factor, doItRight)
  }

  def this () = {
    this(defaultSubject)
  }

}
overloading default scala constructor
3 Answers

Yes, that's not convenient, you'll need to do without default arguments in your auxiliary constructors like:

class X(n: Int, verbose: Boolean = false) {

  def this(n: String, verbose: Boolean) = this(
      Integer.parseInt(n),
      verbose
  )

  def this(n: String) = this(n, false)
}

Mind though that inline (within a function) with default arguments different from each other you can do that:

def main(args: Array[String]): Unit = {

    class Y(n: Int, dummyImplicit: DummyImplicit = null, verbose: Boolean = false) {

        def this(n: String, verbose: Boolean = false) = this(
            Integer.parseInt(n), 
            verbose = verbose
        )
    }
}
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