CODEWITHSUNDEEP
scala
Priyaranjan Swain
Priyaranjan Swain

Reputation: 361

Instantiating an inner class when outer class declared as a var in Scala

When I am declaring my outer class object as a var, I am not able to instantiate the inner class. But when I am making it as a val, I am not getting any error. Why is this happening?

class Outer(name : String ) { ter  =>
  class Iner(name : Inner) {
    println("Printing outer class name : " + ter.name )
    println("Printing inner class name : " + name )
  }
}

object OverRiding extends App {
  var outr : Outer = new Outer("Priyaranjan Outer")
  var inner =  new outr.Iner("Priyaranjan Inner")
}

Upvotes: 2

Views: 80

Answers (1)

Kim Stebel
Kim Stebel

Reputation: 42047

The problem is that in a constructor invocation, the expression referring to the class getting instantiated must be a stable identifier. That is required in the language specification at http://www.scala-lang.org/files/archive/spec/2.11/05-classes-and-objects.html#constructor-invocations

If you look at the definition of a stable identifier, you will see why outr has to be a val:

  • p.x where p is a path and x is a stable member of p. Stable members are packages or members introduced by object definitions or by value definitions of non-volatile types.

Upvotes: 3

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