黑猴子的家：Scala 在特质中重写抽象方法

trait Logger5 {
  def log(msg: String)
}

//因为有super，Scala认为log还是一个抽象方法
trait TimestampLogger5 extends Logger5 {
  abstract override def log(msg: String) {
    super.log(new java.util.Date() + " " + msg)
  }
}

trait ShortLogger5 extends Logger5 {
  abstract override def log(msg: String) {
    super.log(if (msg.length <= 15) msg else s"${msg.substring(0, 12)}...")
  }
}

trait ConsoleLogger5 extends Logger5 {
  override def log(msg: String) {
    println(msg)
  }
}

class Account5 {
  protected var balance = 0.0
}

abstract class SavingsAccount5 extends Account2 with Logger5 {
  def withdraw(amount: Double) {
    if (amount > balance) log("余额不足")
    else balance -= amount
  }
}

object Main5 extends App {
  //这里可以根据5的知识点理解此处
  //在特质中重写抽象方法从右向左
  val acct1 = new SavingsAccount5 with ConsoleLogger5 with TimestampLogger5 with ShortLogger5
  acct1.withdraw(100)
}

尖叫提示：实例化的时候，是从左往右，调用的时候是从右往左.
复写的是抽象的，override是可以省略的，复写的不是抽象的，override是不可以省略的，最好都加上override关键字