ScalaÖ®Äæ±ä

class Master
class Professional extends Master
class Card[-T](val name:String)  //Ö§³ÖÄæ±ä£¬¸¸ÀàÀ´Á˵±È»¿ÉÒÔ
class  Worker
object Test {
  def enterMeet(card: Card[Professional]): Unit = {
    println("welcome to this party!" + card.name)
  }

  def main(args: Array[String]): Unit = {
    val card1 = new Card[Master]("master")
    enterMeet(card1)

    val card2 = new Card[Professional]("professional")
    enterMeet(card2)

    /*val card3 = new Card[Worker]("worker")
    enterMeet(card3)*/
  }
}