named.scala

class A { 
  def f(x: Int, y: Int) = ((x, y)) 
  def name = "A"
}
  
  
class B extends A { 
  override def f(y: Int, x: Int) = ((y, x)) 
  override def  name="B"
}
  

object Test {
  val b = new B
  def main(args: Array[String]): Unit = {
    // the upcast doesn't "undo" the override, of course
    println((b:A).name)  // B
    println((b:B).name)  // B
    
    // wrong!  should be (2,1)
    println((b: A).f(x = 1, y = 2))  // (1,2)
    println((b: B).f(x = 1, y = 2))  // (2,1)
    println((b: A).f(1, 2))          // (1,2)
    println((b: B).f(1, 2))          // (1,2)
  }
}