On Thu, Oct 28, 2010 at 6:55 AM, Pablo G.F <[email protected]> wrote:
> But when I create the menu I have to write the behaviour of each
> widget (when hide/show etc), so I have to instance them. I know what
> you mean by using Singleton but with that approach I can specify the
> behaviour, because they're not created yet.
>
No, you don't have to instantiate them every time to accomplish what you
need to do. Singletons are capable of handling these situations. All that it
requires is that you add static methods to your class for what ever behavior
you want to exercise on the widget. To show the widget all you would then
need to do would be to call YourWidgetClass.getInstance().show() and to hide
it YourWidgetClass.getInstance().hide().
In essence you are providing a static api via encapsulation and each static
method's implementation does the actual work of manipulating the widget. For
example, YourWidgetClass.getInstance().show() would be implemented as
follows:
public static void show(){
instance.show();
}
> What I want is a way to create a menu with widgets associated to it
> and work like a standard web app with html pages, showing the widget
> requested in the menu and hiding the other ones. But the problem is
> that I´d like not having to instance all widgets at the beggining, but
> I don´t see any other way to give them the correct behaviour.
>
> Singleton do not require you instance them when your app starts. They will
be instanced when you call their their static factory method .getInstance()
and only then. Also, remember that on your client the code running is
Javascript which performs garbage collection. At any point you can 'delete'
the singletons by calling their api methods to handle deletion from the dom
and then follow up with calling the widget's apis that do any further
cleaning up. Just remember to set instance to null when you do so that your
next call to YourWidgetClass.getInstance() wont fail.
Any other help?
>
> Thx
>
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>
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Jeff
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