scala學習：特質Trait

特質 Trait

Trait可堆疊特性

可自由組合你的算法，很是靈活。越靠後的特質越先執行。

特質使用的線性化解讀super

abstract class IntQueue {
      def get(): Int

      def put(x: Int)
    }

    class BasicIntQueue extends IntQueue {

      private val buf = new ArrayBuffer[Int]()

      override def get(): Int = buf.remove(0)

      override def put(x: Int): Unit = buf += x
    }

    trait Doubling extends IntQueue {
      abstract override def put(x: Int): Unit = super.put(2 * x)
    }

    trait Increming extends IntQueue {
      abstract override def put(x: Int): Unit = super.put(x + 1)
    }

    trait Filtering extends IntQueue {
      abstract override def put(x: Int): Unit = if (x > 0) super.put(x)
    }


    val myqueue1 = new BasicIntQueue with Doubling with Filtering with Increming
    myqueue1.put(1)
    println(myqueue1.get())

    val myqueue2 = new BasicIntQueue with Increming with Filtering with Doubling
    myqueue2.put(1)
    println(myqueue2.get())

    val myQueue = new BasicIntQueue with Doubling with Increming with Filtering
    myQueue.put(-1)
    println(myQueue.get())

要特質仍是不要？

• 若是某個行爲不會被複用
  用具體的類
• 若是某個行爲可能被用於多個互不相關的類
  用特質，只有特質才能被混入類繼承關係中位於不一樣組成部分的類
• 若是想從Java代碼中繼承某個行爲
  用抽象類
• 上述問題都考慮以後，仍然沒有答案試試特質吧