Scala之逆变

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class Masterclass Professional extends Masterclass Card[-T](val name:String)  //支持逆变,父类来了当然可以class  Workerobject 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)*/  }}

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