You're correct about static final. Didn't think of that [?].
But still I think there is room for improvement:
Consider this use case that is quite clumsy to implement as it is today:
public class APageThatContainsAGrid {
@Persist private int rowsPerPage = 10; // forbidden!
void onAction(int rows) {
this.rowsPerPage = rows;
}
}
and in the template a <t:grid rowsPerPage="rowsPerPage" .../> and a couple
of action links for modifying rowsPerPage.
Why is it prohibited to initialize rowsPerPage in the declaration? An int is
definitely immutable. It's not even an object...
Olle
2008/12/15 Thiago H. de Paula Figueiredo <thiag...@gmail.com>
> Em Mon, 15 Dec 2008 06:47:18 -0300, Olle Hallin <olle.hal...@gmail.com>
> escreveu:
>
> Hi,
>>
>
> Hi!
>
> Beginning with 5.0.17 is is forbidden to have initial values on page
>> members, in order to prohibit state leakage between sessions.
>> This is fine, since it prevents bugs that can be very tricky to isolate.
>>
>
> You're right.
>
> This contradicts to the Tapestry principle *the simplest choice should be
>> the correct choice.*
>>
>
> I don't think so. You have to remember that Tapestry polls page instances,
> so, after one request, Tapestry must restart the page fields values. And
> that the value of a non-primitive field is a reference to an object, not an
> object itself.
>
> IMHO it should be ok to initialize the member in the declaration if it can
>> be guaranteed that the value is immutable.
>>
>
> IMHO, the best way to declare a field that is immutable is to make it final
> and static (i.e. constant) for it, not a private field. ;)
>
> --
> Thiago H. de Paula Figueiredo
> Independent Java consultant, developer, and instructor
> http://www.arsmachina.com.br/thiago
>
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>
--
Olle Hallin
Senior Java Developer and Architect
olle.hal...@crisp.se
www.crisp.se
