On Friday, September 7, 2012 12:21:19 PM UTC+2, Francois Marot wrote:
>
> Hi all,
>
> I'll have to set the basics for a in-house framework and can't make my
> mind on the basic Presenter interface. Is it better to use HasWidgets or
> AcceptsOneWidget ? This would lead to:
>
>
> public interface Presenter {
> public void go(final HasWidgets container);
> }
>
> or
>
> public interface Presenter {
> public void go(final AcceptsOneWidget container);
> }
>
> The former is more generic I think but you always have to think about
> adding the line container.clear() in your implementations. In the latter,
> it's more straightforward (container.setWidget(myView) ) and it is clearer
> as it's enforce the responsibility on the depper Presenter to provide only
> one widget. It's his responsability to group every widget into one
> container before calling setWidget().
> I prefer the latter but it seems that more components implement HasWidgets
> so in the end the former would be easier to developp. What do you think ?
>
> For the record, I was forced to develop a wrapper
> (HasWidgetsToAcceptsOneWidgetWrapper) in order to pass the RootLayoutPanel
> to my first Presenter using the latter method. Here's the dirty code:
> public class HasWidgetsToAcceptsOneWidgetWrapper implements
> AcceptsOneWidget {
> private HasWidgets wrapped;
>
> public HasWidgetsToAcceptsOneWidgetWrapper(HasWidgets wrapped) {
> this.wrapped = wrapped;
> }
>
> public void setWidget(IsWidget widgetToAdd) {
> wrapped.clear();
> wrapped.add(widgetToAdd.asWidget());
> }
>
> }
>
I suppose from that last comment that your Presenter interface is seen by
objects manipulating the "MVP component", i.e. it's not the presenter "as
seen by the view".
Anyway, in either case, it shouldn't be the responsibility of the component
to display itself, but rather the responsibility of some sort of
conductor/manager/controller. So just have your presenter implement
IsWidget and you're done.
As an added bonus, because it's an IsWidget, you can use it anywhere a
widget is expected/accepted, including in UiBinder templates.
To answer your question though, it strikes me as odd to use HasWidgets
here: you really want to give your component the power (and responsibility)
to clear() its container? or add() more than one widget to it? or inspect
(via interator()) the widgets already contained in it and possibly remove()
some of them? (how about removing all but the first 2, adding itself and
adding the removed widgets back in, to simulate an insert?)
No, really, you don't want HasWidgets, AcceptsOneWidget is the way to go;
or IsWidget as I said above.
But all of this really depends how you're intending to use your "Presenter"
interface. I'm not familiar with that approach (first and foremost: I see
MVP as an implementation detail, the outside world simply deals with a
"component" and it doesn't matter whether it uses MVP internally or not).
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