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https://issues.apache.org/jira/browse/WICKET-1312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12604674#action_12604674
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James Carman commented on WICKET-1312:
--------------------------------------

Are we going to introduce this stuff in 1.4?  I thought 1.4 was all about 
generification?

> Generic inter-component event mechanism
> ---------------------------------------
>
>                 Key: WICKET-1312
>                 URL: https://issues.apache.org/jira/browse/WICKET-1312
>             Project: Wicket
>          Issue Type: New Feature
>          Components: wicket-extensions
>    Affects Versions: 1.3.0-final
>            Reporter: Timo Rantalaiho
>             Fix For: 1.4-M3
>
>         Attachments: event-handler-with-testcase.zip, 
> Generic_EventBroadcaster.patch, 
> Generic_EventBroadcaster_glued_in_Component.patch
>
>
> The attached patch provides a generic mechanism for transmitting 
> inter-component events within a page. This has grown primarily from the need 
> to repaint all relevant ajax components after an event, but can be used also 
> in non-ajax environments such as after normal form submits.
> The basic idea is to fire an IVisitor on the page of the component sending an 
> event, giving as an argument an event-specific listener interface that must 
> be implemented by the components willing to receive the events. They can then 
> do whatever they need such as add themselves to the AjaxRequestTarget that 
> can be supplied in the event.
> Sometimes the basic Wicket mechanisms such as sharing a model are not enough; 
> particularly repainting all relevant components in Ajax events gets tedious 
> if the components are far away from each other in a complex DOM tree.
> The benefits of this approach are
> - loose coupling between the sending and receiving end
> - however, because of strong static typing it's easy enough to find with an 
> IDE from where the events are broadcasted and where they are received
> - good testability (EventBroadcaster can be mocked on the sending end, and 
> event handlers tested directly on the receiving end, possibly with mock 
> events)
> - no need the keep references to Component instances or their paths (which 
> could have been problematic on repeaters)
> (This is not a real observer or listener pattern implementation because the 
> components cannot register and unregister themselves dynamically, but 
> "registering" is handled statically on a class basis by implementing the 
> relevant event receiver interface.)

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