Re: Are Errors in a Future body rethrown, as per the documentation?

Hi Andrew,

I think that behaviour was changed later on.
See the revision history / Issues for details.

On Mon, Jul 13, 2015 at 10:09 PM, Andrew Phillips <[email protected]>
wrote:

> Hi all
>
> With regard to the handling of Errors, the "Futures and Promises"
> documentation [1] states:
>
> ExecutionException - stored when the computation fails due to an
>> unhandled InterruptedException, Error or a
>> scala.util.control.ControlThrowable. In this case the ExecutionException
>> has the unhandled exception as its cause. *These exceptions are rethrown
>> in the thread executing the failed asynchronous computation.*
>
>
> Is this latter statement true in general, e.g. also if you supply your own
> ExecutionContext? Or does it depend on the ExecutionContext implementation?
>
> In this example at least, nothing seems to be rethrown (or passed to
> reportFailure, for that matter):
>
> Welcome to Scala version 2.11.6 (Java HotSpot(TM) 64-Bit Server VM, Java
> 1.7.0_40).
>
>
> import scala.concurrent.Future
> import scala.concurrent.ExecutionContext
> import scala.util.{Failure, Success}
>
>
> implicit object SameThreadExecutionContext extends ExecutionContext {
>   override def execute(runnable: Runnable): Unit = {
>     println("DEBUG: running " + runnable)
>     runnable.run()
>   }
>   override def reportFailure(t: Throwable): Unit = ??? // never called?
> }
>
> scala> Future { throw new Error("bang!") }.value
> DEBUG: running
> scala.concurrent.impl.Future$PromiseCompletingRunnable@887b5d0
> res1: Option[scala.util.Try[Nothing]] =
> Some(Failure(java.util.concurrent.ExecutionException: Boxed Error))
>
>
> Am I missing something or misreading the docs here?
>
> Regards
>
> ap
>
> [1] http://docs.scala-lang.org/overviews/core/futures.html#exceptions
>
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