/** File "SquareTest4.scala" by KWR for CSE250, Spring 2022.
    For "Square Is-A Rectangle?" problem.  DOES NOT COMPILE
    V4 tests whether match can act like Java instanceof
 */
class Rectangle(val length: Double, val width: Double) {
   def dims = s"$length x $width"
}

case class Square(side: Double) extends Rectangle(side, side) {
   //def side = width
}

object SquareTest4 extends App {
   var r = new Rectangle(2.0,3.0)
   r = new Square(3.0)   
   //r.length = 4.0    //caught by compiler since *data* is immutable
   println("The Square object has dimensions " + r.dims)
   val s = new Square(7.0)
   println(s"Does the Square object have a side? ${s.side}")

   println("\nDoes the subclass provide matchable structure?")

   def whatami(r: Rectangle): String = r match {
      case Square(sd) => "Square of side " + sd   //the Square case is OK
      case Rectangle(len,wd) => "Rectangle of length " + len + " and width " + wd
   }
}