Hi Jesse,
Thanks for that reply.
If I read it correctly, it sounds, simply, like the framework is missing this
feature. It's a pretty common thing to ask for listener call-backs on
framework events. ("Listener" here in the generic sense rather than the way
tapestry uses the term for direct-link targets.) In short, this sounds like a
design over-sight. It's common when beans are bound to be able to receive a
call-back -- Hibernate, for example, offers this. So much of Tapestry seems
"automagic" I'm surprised that there's no way to register to be informed of the
events as they occur.
If Howard's reading this perhaps he has a better perspective that he may offer.
Thanks,
Ezra Epstein
Amazon.com - Developer Tools
206-266-2259
-----Original Message-----
From: Jesse Kuhnert [mailto:[EMAIL PROTECTED]
Sent: Friday, October 06, 2006 7:22 PM
To: Tapestry users
Subject: Re: How to observe property binding events
Yes, but the usefulness of my answer largely depends on how clever/efficient
you are trying to be doing it.
Now, there is IBinding. The one object to bind them all ;)
If you work your way down the type hierarchy you'll find AbstractBinding, which
holds the method you care about most - "setObject". This will be called by
tapestry when managing all of the page properties "automagically"
for you.
Some of the magic happens in (for your exact case at least)
org.apache.tapestry.enhance.ParameterPropertyWorker.
The other half of the work happens in each specific binding implementation that
will handle these set/get object calls..(Like ognl bindings, etc..)
I'm not sure where you are going with this but I guess you could use the
hivemind chain of command service sort of configuration (like I did for
org.apache.tapestry.services.ComponentRenderWorker ) to generically call a
single interface method for a hivemind configuration point...Then you can
contribute as many workers into the chain you like if you decide that you have
more than one use for it.
Again...Not knowing what you are doing - and taking the exact parameters given
I'd probably extend and override the default ParameterPropertyWorker (a
hivemind service, so replacing it inline with what Tapestry does already should
be easy ) and just override whatever section of code I needed to in that
implementation to inject + call my service reference.
It may look a little complicated in there at first, but the whole
org.apache.tapestry.enhance package is filled with lots of different
enhancement works - and most of them inject a service into the object they work
on...So finding an easier to follow worker to reference before modifying
ParameterPropertyWorker might be easier.
Hope that helps.
On 10/6/06, Epstein, Ezra <[EMAIL PROTECTED]> wrote:
>
> I've got a component which accepts a parameter. I want to listen
> (receive a callback) when the parameter is set (bound). Does Tapestry
> provide such a facility?
>
> Thanks,
>
> Ezra Epstein
>
>
>
>
--
Jesse Kuhnert
Tapestry/Dojo/(and a dash of TestNG), team member/developer
Open source based consulting work centered around dojo/tapestry/tacos/hivemind.
http://blog.opencomponentry.com
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