Stackable Trait

StackableTrait.scala

//every power got specific points
trait Power {
  def points: Int
}

trait Speed extends Power {
  //abstract override is the special identifier for stackable feature
  //super is now referencing the previous trait in the linearization that is, the previous in the declaration
  abstract override def points = super.points + 10
}

trait Strength extends Power {
  abstract override def points = super.points + 5
}

//a SuperHero always have at least one power
class SuperHero {
  self: Power =>
  
  //because even with bullshit powers u still a SuperHero
  override def points = 1
}

val superman = new SuperHero() with Speed with Strength

//because there is one and only Flash Gordon
object Flash extends SuperHero with Speed

val spoints = superman.points
val fpoints = Flash.points
println(s"Superman got $spoints points")
println(s"Flash got $fpoints points")

//prints:
//Superman got 16 points
//Flash got 11 points