Fabio Fioretti wrote:
On 8/3/07, Al Maw <[EMAIL PROTECTED]> wrote:
If you're going to be using the previous page in your new page (for
example, to provide a link back to it) then you need a reference to it.
You may as well pass this in the constructor.
But is it the only way to do this really?
An automatic mechanism to get the caller page without passing it in
the constructor would be cool. Does it exist?
Why would it be cool? The method required at the moment is far more
explicit and obvious. In particular, it's just plain Java and not some
magic.
If have some automatic mechanism it would need to cope with:
- What happens when you do redirects? Particularly, what if you throw
RestartResponseException() in a page's constructor?
- What if you came via a stateless page?
- What happens when you access pages from two page maps simultaneously?
- How do you make sure that the previous page that you're going to use
in your new page instance doesn't disappear out of the page map
stack because no one has used it recently and no one has a reference
to it any more?
That said, if you really want to you could implement this yourself in
any one of a number of ways.
For example, you could keep the last rendered Page instance in a custom
Session and have a base page class of yours call
yourSession.setLastRendered(this) in its onDetach() method. There may be
race conditions if people are browsing pages in two tabs at once in
different page maps, but you'll probably never notice them. Or you could
do something similar but with a ThreadLocal you can set in a custom
RequestCycle.
All of this is really complex and unobvious compared to just passing the
page in in the constructor, which is reliable, easy and simple. So, err,
why don't you just do that?
Regards,
Al
--
Alastair Maw
Wicket-biased blog at http://herebebeasties.com
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