Question

I’m a little stumped at how silly this problem is and have a serious mindblank, but I thought I might ask anyway.

I have an object Foo, with several fields. I want a method that can change any of its fields depending on which one is passed in as a parameter. Like so:

class Foo {
    var x = 0
    var y = 0
}

class Bar {
    def changeFooField(field : Int) = {
        field = 1        
    }
}

Can I not use it like so?:

changeFooField(foo.x)

If not, how do I accomplish this?

Answer 1

No you cannot. You’ll need to enclose the field value into an object:

class Field[T]( var value: T )

class Foo {
  val x = new Field(0)
  val y = new Field(0)
}

class Bar {
  def changeFooField( field: Field[Int] ) {
    field.value = 1
  } 
}

val f = new Foo
(new Bar).changeFooField( f.x )
println( f.x.value + " / " + f.y.value ) // prints "1 / 0"