Question

Short of renaming the constructor parameter in the primary constructor of class B, what change can I make to the following code (without changing its function) so that Scala will compile it successfully?

Example:

class A(var a: Int)
class B(a: Int) extends A(a) {
  def inc(value: Int) { this.a += value }
}

Error:

$ scala construct.scala
construct.scala:3: error: reassignment to val
  def inc(value: Int) { this.a += value }
                               ^
one error found

I raised this question in an answer to my previous question, “In Scala, how do you define a local parameter in the primary constructor of a class?”.

Answer 1

class A(var a: Int)
class B(a: Int) extends A(a) {
  def inc(value: Int) { (this: A).a += value }
}