cirle-ellipse-inheritance.scala

class Duple(val first : float, val second : float)

class DiagDuple(val sole : float) extends Duple(sole, sole) 

class Ellipse[-F <: Duple](foci : F) {
    private var m_foci : Duple = foci
    def foci : Duple = m_foci
    def foci_=(foci : F) = m_foci = foci
}

class Circle(center : DiagDuple) extends Ellipse[DiagDuple](center) 

object MyApp extends Application {
    def calcExc[T <: Duple](el : Ellipse[T]) = el.foci.first - el.foci.second
    Console println calcExc(new Circle(new DiagDuple(42)))
}