Event

Prologue supports both startup and shutdown events. startup events will be only executed once for each thread. In contrast, shutdown events will be executed once after the main loop.

Let's first look at the structure of Event, you can see that Event supports both synchronous and asynchronous closure function pointers.

type
  AsyncEvent* = proc(): Future[void] {.closure, gcsafe.}
  SyncEvent* = proc() {.closure, gcsafe.}

  Event* = object
    case async*: bool
    of true:
      asyncHandler*: AsyncEvent
    of false:
      syncHandler*: SyncEvent

You can use initEvent and pass function pointers to create Event.

proc initEvent*(handler: AsyncEvent): Event {.inline.} =
  Event(async: true, asyncHandler: handler)

proc initEvent*(handler: SyncEvent): Event {.inline.} =
  Event(async: false, syncHandler: handler)

newApp has startup and shutdown parameters. You can pass a sequence of events to newApp.

proc newApp*(settings: Settings, middlewares: sink seq[HandlerAsync] = @[],
             startup: seq[Event] = @[], shutdown: seq[Event] = @[],
             errorHandlerTable = DefaultErrorHandler,
             appData = newStringTable(mode = modeCaseSensitive)): Prologue =

Here is an example for a startup event (A shutdown event has the same usage as a startup event).

proc setLoggingLevel() =
  addHandler(newConsoleLogger())
  logging.setLogFilter(lvlInfo)


let 
  event = initEvent(setLoggingLevel)

var
  app = newApp(settings = settings, startup = @[event])