斯卡拉 – 蛋糕模式 – 为什么这么复杂

我正在阅读this博客.

该博客的示例代码是：

case class User (name:String,email:String,supervisorId:Int,firstName:String,lastName:String)

trait UserRepository {
  def get(id: Int): User
  def find(username: String): User
}
trait UserRepositoryComponent {

  def userRepository: UserRepository

  trait UserRepository {
    def get(id: Int): User
    def find(username: String): User
  }
}
trait Users {
  this: UserRepositoryComponent =>

  def getUser(id: Int): User = {
    userRepository.get(id)
  }

  def findUser(username: String): User = {
    userRepository.find(username)
  }
}
trait UserInfo extends Users {
  this: UserRepositoryComponent =>

  def userEmail(id: Int): String = {
    getUser(id).email
  }

  def userInfo(username: String): Map[String,String] = {
    val user = findUser(username)
    val boss = getUser(user.supervisorId)
    Map(
      "fullName" -> s"${user.firstName} ${user.lastName}","email" -> s"${user.email}","boss" -> s"${boss.firstName} ${boss.lastName}"
    )
  }
}
trait UserRepositoryComponentImpl extends UserRepositoryComponent {

  def userRepository = new UserRepositoryImpl

  class UserRepositoryImpl extends UserRepository {

    def get(id: Int) = {
      ???
    }

    def find(username: String) = {
      ???
    }
  }
}

object UserInfoImpl extends
    UserInfo with
    UserRepositoryComponentImpl

我可以通过删除用户来简化该代码：

package simple {

  case class User(name: String,email: String,supervisorId: Int,firstName: String,lastName: String)

  trait UserRepository {
    def get(id: Int): User

    def find(username: String): User
  }

  trait UserRepositoryComponent {

    def userRepository: UserRepository

    trait UserRepository {
      def get(id: Int): User

      def find(username: String): User
    }

  }

  trait UserInfo {
    this: UserRepositoryComponent =>

    def userEmail(id: Int): String = {
      userRepository.get(id).email
    }

    def userInfo(username: String): Map[String,String] = {
      val user = userRepository.find(username)
      val boss = userRepository.get(user.supervisorId)
      Map(
        "fullName" -> s"${user.firstName} ${user.lastName}","boss" -> s"${boss.firstName} ${boss.lastName}"
      )
    }
  }

  trait UserRepositoryComponentImpl extends UserRepositoryComponent {

    def userRepository = new UserRepositoryImpl

    class UserRepositoryImpl extends UserRepository {

      def get(id: Int) = {
        ???
      }

      def find(username: String) = {
        ???
      }
    }

  }

  object UserInfoImpl extends
    UserInfo with
    UserRepositoryComponentImpl

}

它编译得很好.

1)为什么博客中的代码如此复杂？

2)这是使用蛋糕模式的惯用方法吗？

3)为什么在这个例子中需要Users类？

4)那是蛋糕模式看起来的样子(看似不必要的用户类吗？

5)或简化版是否正常？