Delayed messages

[matmleave]

• A general case is that one may want to send a message later, like do something after 10 secs, or do something when mouse clicks next time, instead of doing something right now
• planned effect:

  type LayerMsg
  = ...
  | LayerMsgDelayedOnce (EnvC -> Maybe LayerMsg)       -- triggered only once
  | LayerMsgDelayed (EnvC -> Maybe LayerMsg)           -- always valid

• example1: If one want to send 1 to a layer called "A" when mouse is clicked next time

  updateModel env lmsg model =
  ...
  let cond fenv =
      case fenv.msg of
          MouseDown _ _ ->
              Just (LayerIntMsg 1)
          _ ->
              Nothing
  in
  (model, [(LayerName "A", LayerMsgDelayedOnce cond)], env)

• example2: If one want to send 1 to layer "A" after some time, then write

  updateModel env lmsg model =
  ...
  let cond fenv =
      case fenv.msg of
          Tick t ->
              let cond2 fenv2 =
                  case fenv2.msg of
                      Tick t2 ->
                          if (toSecond utc t2) >= (toSecond utc t) + 100 then
                              Just (LayerIntMsg 1)
                          else
                              Nothing
                      _ ->
                          Nothing
              in 
              Just (LayerMsgDelayedOnce cond2)
          _ ->
              Nothing
  (model, [(LayerName "A", LayerMsgDelayedOnce cond)], env)

  this will start counting time after next Tick.

[linsyking]

This could be implemented by event bus subsystem which might be implemented as a component.

[Monolitho]

Yes... But since it is a highly-demanded feature in game-development, I still would say it is necessary to add it into messenger.

[linsyking]

Using the latest messenger, this could be implemented easily as a global component. We could implement this in extra.

Yes... But since it is a highly-demanded feature in game-development, I still would say it is necessary to add it into messenger.