We have discussed this issue at length on our team, as we're building an application that will eventually grow to be quite large. There are certainly pros and cons to each approach (nesting presenters vs a flat lookup at the AppController level).
Nested Pros Handy place to hook up a hierarchical location change framework Chain of responsibility for loading data (parents can load data from an rpc and pass it down to child presenters to ensure state is maintained) Easy re-use of groups of presenters, flexibility to mix and match. Plays well with nested display objects, so if you've got a TabPanel, each tab can be driven by a separate presenter and the panel itself can have a presenter to load data common to all tabs. Nested Cons Can be more difficult to analyze the layout of the application without a single class where all presenter relationships are defined Does not play well with view classes which have components that need to be driven by multiple presenters. For example, if you have a ui.xml with two main areas and you want a presenter to handle each, using nested presenters requires more spaghetti code that just having a couple of flat ones. It can be more difficult to write unit tests against parent presenters, because you have to take into account instantiation and operation of child presenters... This can impact the complexity of the mock objects you must create. Anyway, we've chosen to go with nested presenters, but I would say the vote on our team for this was split 4/2, so clearly even for us not everybody is in love with it. On Feb 5, 5:00 pm, Sydney <[email protected]> wrote: > I try to implement the best practices discussed in the article "Large > scale application development and MVP". My application is designed > using several widgets: > MainContainerWidget: a DockLayoutPanel > NorthWidget: a widget in the north region of the main container > CenterWidget: a widget in the center region of the main container. > This widget is a composite of two widget (TopWidget and BottomWidget) > SouthWidget: a widget in the south region of the main container. > > 1/ I created a Presenter for each widget. The CenterPresenter contains > a TopPresenter and a BottomPresenter that are instanciated in the > constructor of CenterPresenter. > > public CenterPresenter(HandlerManager eventBus, Display display) { > this.eventBus = eventBus; > this.display = display; > topPresenter = new TopPresenter(eventBus, new TopWidget()); > bottomPresenter = new BottomPresenter(eventBus, new > BottomWidget()); > } > > @Override > public void go(HasWidgets container) { > bind(); > container.clear(); > container.add(display.asWidget()); > } > > private void bind() { > topPresenter.bind(); > bottomPresenter.bind(); > } > > So basically when the CenterPresenter is created in the AppController > class, it would create all its child presenters and call the bind > methods. Does it seem a good approach or is there a better way? -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
