/** Account */
class Account extends ConsoleLogger with ShortLogger with TimestampLogger {
  private var balance = 0
  log("Account created")

  def deposit(amount: Int) {
    balance += amount
    log("deposit of " + amount + ". new balance: " + balance)
  }
}

/** Logger */
trait Logger {
  def log(msg: String) // abstract method
}

trait ConsoleLogger extends Logger {
  def log(msg: String) { // concrete method
    println(msg)
  }
}

trait TimestampLogger extends Logger {
  // abstract for it might call super[Logger].log
  abstract override def log(msg: String) {
    super.log(new java.util.Date() + " " + msg)
  }
}

trait ShortLogger extends Logger {
  val maxLength = 15
  // abstract for it might call super[Logger].log
  abstract override def log(msg: String) {
    super.log(
        if (msg.length <= maxLength) msg
        else msg.take(maxLength - 3) + "..."
        )
  }
}