Question

I’m trying to make an API library for our web services, and I’m wondering if it’s possible to do something like this:

abstract class UserRequest(val userId: Int) {
  def success(message: String)
  def error(error: ApiError)
}

api.invokeRequest(new UserRequest(121) {
  override def success(message: String) = {
    // handle success
  }

  override def error(error: ApiError) = {
    // handle the error
  }
}

I’m talking about passing parameters to the anonymous inner class, and also overriding the two methods.

I’m extremely new to Scala, and I realize my syntax might be completely wrong. I’m just trying to come up with a good design for this library before I start coding it.

I’m willing to take suggestions for this, if I’m doing it the completely wrong way, or if there’s a better way.

The idea is that the API will take some sort of request object, use it to make a request in a thread via http, and when the response has been made, somehow signal back to the caller if the request was a success or an error. The request/error functions have to be executed on the main thread.

Answer 1

Does the following look like what you want?

scala> abstract class UserRequest(val userId: Int) {
         def success(message: String)
         def error(error: String)
       }

scala> trait Api {def invokeRequest(r: UserRequest): Unit}

api: java.lang.Object with Api = $anon$1@ce2db0

scala> val api = new Api {
         def invokeRequest(r: UserRequest) = {
            //some request handling here...., always successful in our case
            if (true) r.success("succeeded") else r.error("failed")
         } 
       }


scala> api.invokeRequest(new UserRequest(121) {
          def success(message: String) = println("user request 121 got success: " + message)

          def error(error: String) = println("user 121 request got error: " + error)
})
user request 121 got success: succeeded