OrderWithWorkaround.scala

import Order.Order

object OrderWithWorkaround extends App {

  class BuyWithWorkaround(q: Int) extends {
    val quantity = q
  } with Order

  class SellWithWorkaround(q: Int) extends {
    val quantity = q
  } with Order

  object TradeWithWorkaround {
    def buy(q: Int): BuyWithWorkaround = new BuyWithWorkaround(q)
    def sell(q: Int): SellWithWorkaround = new SellWithWorkaround(q)
  }

  val buy2 = TradeWithWorkaround.buy(100)
  println(buy2.quantity)
  println(buy2.printQuantity)
}