Re: HowTo use GWT EvenBus to schedule OpenEvent -> CloseEvent sequence

[Michael Joyner]

I don't know if it will help any, but we had issues with the eventbus firing immediately synchronously (not good if the event for a widget fires before said widget finishes attaching and hooking up to receive events!). We ended up creating a deferred eventbus. Seems like you should be able to extend it and get what you want. We create our eventbus as "new DeferredEventBus(new SimpleEventBus())". import com.google.gwt.core.client.Scheduler; import com.google.web.bindery.event.shared.Event; import com.google.web.bindery.event.shared.Event.Type; import com.google.web.bindery.event.shared.EventBus; import com.google.web.bindery.event.shared.HandlerRegistration; public class DeferredEventBus extends EventBus {     private final EventBus wrapped;     public DeferredEventBus(EventBus wrappedBus) {         this.wrapped = wrappedBus;       }         @Override     public <H> HandlerRegistration addHandler(Type<H> type, H handler) {         return wrapped.addHandler(type, handler);     }     @Override     public <H> HandlerRegistration addHandlerToSource(Type<H> type, Object source, H handler) {         return wrapped.addHandlerToSource(type, source, handler);     }     @Override     public void fireEvent(Event<?> event) {         Scheduler.get().scheduleDeferred(() ->wrapped.fireEvent(event));     }     @Override     public void fireEventFromSource(Event<?> event, Object source) {         Scheduler.get().scheduleDeferred(() ->wrapped.fireEventFromSource(event, source));     } } On 10/26/2016 12:51 PM, vitrums wrote: [ Original post on StackOverflow http://stackoverflow.com/questions/40130383/howto-use-gwt-evenbus-to-schedule-openevent-closeevent-sequence ] Say we have few handlers for both events. The goal is to make sure, that all OpenEvent handlersfinish before any of CloseEvent handlers start their job. The old EventBus had a reverse order flag, which sometimes helped greatly in these particular cases. I.e. a handler, responsible for launching some process which leads to CloseEvent being fired (i.e. event emitter), usually registers itself to a bus first. Now, due to a synchronous nature of _javascript_ each handler of OpenEvent ends his job before the next handler starts. In my app the first OpenHandler added to a bus is a CloseEvent emitter. Therefore I get an undesirable sequence of calls: 1st handler of OpenEvent -> all CloseEvent handlers -> the rest of OpenEvent handlers. My question is: what's the best practice to establish the desirable behavior? So far as a workaround I use Scheduler.scheduleDeferred(Scheduler.ScheduledCommand cmd) to enqueueEventBus.fireEventFromSource(Event event, Object source) of CloseEvent call to the next browser's event loop tick. p.s. My current thoughts are as follows. I don't want to rely of Timer or Scheduler (though it might be the only option, which I'm not sure about). Also I have no interest in introducing any flag variables, responsible for tracking which event occurred first. Instead, if one looks closer into theSimpleEventBus code, there's a firingDepth counter variable, which only works to delayaddHandler(...) and removeHandler(...) calls. It would be great, if same logic could be applied to order call sequences of handlers for different events. -- You received this message because you are subscribed to the Google Groups "GWT Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-web-toolkit+unsubscr...@googlegroups.com. To post to this group, send email to google-web-toolkit@googlegroups.com. Visit this group at https://groups.google.com/group/google-web-toolkit. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "GWT Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-web-toolkit+unsubscr...@googlegroups.com. To post to this group, send email to google-web-toolkit@googlegroups.com. Visit this group at https://groups.google.com/group/google-web-toolkit. For more options, visit https://groups.google.com/d/optout.