Scala class members and constructor parameters name clash

Question

Consider the following class written in Java:

class NonNegativeDouble {
    private final double value;
    public NonNegativeDouble(double value) {
        this         


        

Answer 1

No, you can't. In Scala, constructor parameters are properties, so it makes no sense to redefine them.

The solution, naturally, is to use another name:

class NonNegativeDouble(initValue: Double) {
  val value = Math.abs(initValue)
}

Used like this, initValue won't be part of the instances created. However, if you use it in a def or a pattern matching declaration, then it becomes a part of every instance of the class.