Category: future

val myFuture = Future {

    // you have no future, you are DOOMED!

    42

    // JK.

}

def gimmeMyPreciousValue(yourArg: Int): Future[String]

object MyService {

  def produceThePreciousValue(theArg: Int): String = "The meaning of your life is " + (theArg / 42)

  def submitTask[A](actualArg: A)(function: A => Unit): Boolean = {

    // send the function to be evaluated on some thread, at the discretion of the scheduling logic

    true

  }

}

def gimmeMyPreciousValue(yourArg: Int): Future[String] = Future {

  MyService.produceThePreciousValue(yourArg)

}

// create an empty promise

val myPromise = Promise[String]()

// extract its future

val myFuture = myPromise.future

// do your thing with the future, assuming it will be filled with a value at some point

val furtherProcessing = myFuture.map(_.toUpperCase())

val asyncCall(promise: Promise[String]): Unit = {

    promise.success("Your value here, your majesty")

}

def gimmeMyPreciousValue(yourArg: Int): Future[String] = {

    // create promise now

    val thePromise = Promise[String]()

    // submit a task to be evaluated later, at the discretion of the service

    // note: if the service is not on the same JVM, you can pass a tuple with the arg and the promise so the service has access to both

    MyService.submit(yourArg) { x: Int =>

        val preciousValue = MyService.producePreciousValue(x)

        thePromise.success(preciousValue)

    }

    // return the future now, so it can be reused by whoever's consuming it

    thePromise.future

}