[
https://issues.apache.org/jira/browse/WICKET-1312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12631484#action_12631484
]
Timo Rantalaiho commented on WICKET-1312:
-----------------------------------------
Hi Martin,
That's a fair enough question, which already came up on the
mailing list so I'll just quote myself
"I wanted to make the code using the framework as clear
and simple as possible, perhaps with the cost of added
complexity inside the framework, and separate onEvent()
methods for different event types feels clearer and more
elegant to me than the instanceof checks. That way, you
can see right away from the signature of the component
class which events it handles. "
http://www.nabble.com/Generic-event-mechanism-(was%3A-loosely-coupled-panels%3A-react-to-model-object-change)-tt15516909.html#a16072330
It's too bad that because of erasure, reflection is needed
to be able to have multiple onEvent() methods for
different types.
> 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: 1.5-M1
>
> 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.)
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
