Question

here’s the basic example.. I can’t get scala to recognize that I want the ability to initialize my class in 2 different ways: via an existing sequence, or using multiple parameters.

The error I receive is:

double definition: method apply:(params:
Int*)chorle.scala.tests.MultiParam and method apply:(pList:
Seq[Int])chorle.scala.tests.MultiParam at line 9 have same type after
erasure: (params: Seq)chorle.scala.tests.MultiParam

Which ok, I get what’s going on here – post compilation both functions result in the same header signature. However, in practice they do not work the same way – I can’t envoke : apply(1,2,3) if I only have the apply(Seq) version… and I can’t envoke apply(seq) the other way around. I am aware of various ways I could patch the actual function call, but how do I address this properly and only once in the class? Thank you!

class MultiParam protected (pList:Seq[Int]) 

object MultiParam {
  def apply(pList:Seq[Int]): MultiParam = new MultiParam(pList)
  def apply(params: Int *): MultiParam = new MultiParam(params)


} 

Answer 1

Well, they can’t be used as is because there’s no way to generate both methods. The only way around it is to disambiguate them:

object MultiParam {
  def apply(pList:Seq[Int]): MultiParam = new MultiParam(pList)
  def apply(param: Int, params: Int *): MultiParam = new MultiParam(param +: params)
  def apply(): MultiParam = new MultiParam(Nil)
}