Order.scala

object Order extends App {
  trait Order {
    val quantity: Int
    val printQuantity: String = s"This order has a quantity of $quantity"
  }

  class Buy(q: Int) extends Order {
    override val quantity: Int = q
  }
  class Sell(q: Int) extends Order {
    override val quantity: Int = q
  }

  object Trade {
    def buy(q: Int): Buy = new Buy(q)
    def sell(q: Int): Sell = new Sell(q)
  }

  val buy1 = Trade.buy(100)
  println(buy1.quantity)
  println(buy1.printQuantity)
}