Try is free in the Future

19 Jan, 2015
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Lately I have seen a few developers consistently use a Try inside of a Future in order to make error handling easier. Here I will investigate if this has any merits or whether a Future on it’s own offers enough error handling.

If you look at the following code there is nothing that a Future can’t supply but a Try can: [scala] import import scala.concurrent.{Await, Future, Awaitable} import scala.concurrent.duration._ import scala.util.{Try, Success, Failure} object Main extends App { // Happy Future val happyFuture = Future { 42 } // Bleak future val bleakFuture = Future { throw new Exception("Mass extinction!") } // We would want to wrap the result into a hypothetical http response case class Response(code: Int, body: String) // This is the handler we will use def handle[T](future: Future[T]): Future[Response] = { { case answer: Int => Response(200, answer.toString) } recover { case t: Throwable => Response(500, "Uh oh!") } } { val result = Await.result(handle(happyFuture), 1 second) println(result) } { val result = Await.result(handle(bleakFuture), 1 second) println(result) } } [/scala] After giving it some thought the only situation where I could imagine Try being useful in conjunction with Future is when awaiting a Future but not wanting to deal with error situations yet. The times I would be awaiting a future are very few in practice though. But when needed something like this migth do: [scala] object TryAwait { def result[T](awaitable: Awaitable[T], atMost: Duration): Try[T] = { Try { Await.result(awaitable, atMost) } } } [/scala] If you do feel that using Trys inside of Futures adds value to your codebase please let me know.

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