Question

我有以下代码：

object Application {

  case class User(id: Long, username: String)
  case class Request(path: String)
  case class WrappedRequest(user: User, request: Request)

  def updateUserAction(implicit request: WrappedRequest) = {
    updateUser("john@mail.com") // <-- I need request.user to be passed implicitly here
  }

  def updateUser(email: String)(implicit user: User) = {
     println(user.username)
  }


  def main(args: Array[String]) = {
    implicit val request = WrappedRequest(User(1L, "john"), Request("/"))
    updateUserAction
  }

}

从上面可以隐式地将 updateUserAction 方法中的 request.user 传递给 updateUser 方法吗？

Answer 1

进行从WrappedRequest到User的隐式转换，以便所有需要WrappedRequest的方法都可以访问隐式User。

implicit def req2User(implicit request: WrappedRequest): User = request.user

Answer 2

喜欢这个吗？

def updateUserAction(implicit request: WrappedRequest) = {
  implicit val user: User = request.user
  updateUser("john@mail.com")
}

Scala：如何隐式传递类隐式实例的属性？

2 个答案: