Generalize PromiseHandler

[PetrosPapapa]

PromiseHandler currently only returns the result of the overall workflow.

The CounterHandler introduced in 0488604 is a good example of how promises can be used to return different things.

It would be nice to generalize the PromiseHandler so that it is simpler to implement handlers that need to return stuff.

So you can implement the CounterHandler like this:

class CounterHandler[T](override val name:String) extends PromiseHandler[T,Int] {   
  private var counter:Int = 0
  def count = counter
  
  override def apply(e:PiEvent[T]) = counter += 1
  override def onSuccess(result:Any) = promise.success(counter)
  override def onFailure(result:Any) = promise.success(counter)
}

The current version of the PromiseHandler that returns the result of the workflow can be named ResultHandler or something like that instead, as a simple instance of the PromiseHandler.

• New PromiseHandler
• ResultHandler
• CounterHandler
• New PromiseHandleFactory
• ResultHandleFactory
• New CounterHandlerFactory
• Resolve things that break in ProcessExecutor.scala and anywhere else