You're not using this feature correctly. It's for the state of the
property when it's returned to the page pool, not for when you use it
on the page.
Implement PageRenderListener in your Java file, then implement
pageBeginRender() and initialize your variables there. You'll be able
to get the proper sequence happening.
Jamie
On Aug 11, 2005, at 10:49 AM, Savitsky, Alex wrote:
So far it has always been alphabetic, but point taken. Still, if
the order
of initialization is pretty much undefined - is there a reliable
way to
specify page properties that depend one on another?
-- Alex
-----Original Message-----
From: Patrick Casey [mailto:[EMAIL PROTECTED]
Sent: Thursday, August 11, 2005 10:45 AM
To: 'Tapestry users'
Subject: RE: Tapestry 3.0.3 - property initialization sequence
I've got $0.25 that says it's probably some variable on a hashmap
internally, so I wouldn't count on it always being alphabetic,
although you
could pretty much assume it won't happen in the same order they're
on the
page :).
--- Pat
-----Original Message-----
From: Savitsky, Alex [mailto:[EMAIL PROTECTED]
Sent: Thursday, August 11, 2005 7:33 AM
To: '[email protected]'
Subject: Tapestry 3.0.3 - property initialization sequence
Hi,
Found a funny quirk in the way page properties are initialized, that
can possibly lead to exceptions:
Test.page:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE page-specification
PUBLIC "-//Apache Software Foundation//Tapestry Specification
3.0//EN"
"http://jakarta.apache.org/tapestry/dtd/Tapestry_3_0.dtd
<http://jakarta.apache.org/tapestry/dtd/Tapestry_3_0.dtd> ">
<page-specification class="org.apache.tapestry.html.BasePage">
<property-specification name="p2"
type="java.lang.Integer">1</property-specification>
<property-specification name="p1"
type="java.lang.Integer">p2.intValue() + 1</property-specification>
</page-specification>
Load the page, get an NPE. Reason? I went in with a debugger to
check,
and it looks like the properties are initialized in alphabetic order
(so that "p1" is initialized BEFORE "p2"). Swap the variable names
(so
that "p2" depend on "p1", instead of the other way around), and the
page loads fine.
Am I missing something, or it is really being done that way? In this
case, is it really the best way to handle that? Wouldn't a some sort
of endless loop be better, so that initialization of "dependent"
properties could be deferred until their "parent" properties are
initialized?
I haven't tried Tapestry 4 yet, does anyone know, was that... m-m-
m...
"feature" fixed there?
Regards,
Alex Savitsky
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