It's just a matter of understanding how anonymous inner classes (or named inner classes) work. It's not a Wicket thing. It's a Java thing. So, if it's confusing, take it up with Oracle.
On Tue, May 18, 2010 at 3:05 AM, Rik van der Kleij <rikvdkl...@gmail.com> wrote: > To mine opinion this Best practise is confusing. It is just a matter of do > not share Wicket components between pages because Wicket will not detect > while serializing pages that components are already serialized. > > The case of sharing anonymous IModel implementations is a special case > because implicitly a Wicket component is shared. So you have to be careful > with sharing models. > > Regards, > Rik > > > > On 17 mei 2010, at 18:55, Jeremy Thomerson wrote: > >> You should use PageReference (Page#getPageReference()). >> >> -- >> Jeremy Thomerson >> http://www.wickettraining.com >> >> >> >> On Sun, May 16, 2010 at 11:52 PM, Rik van der Kleij >> <rikvdkl...@gmail.com>wrote: >> >>> Hi Jeremy, >>> >>> So an instance field inside a page that points to another page is also >>> something you should avoid? In our application we using this pattern a lot >>> (for going back to previous page) but it never seems to be any problem. So >>> probably because our pages don't consume a lot of memory. >>> >>> Regards, >>> Rik >>> >>> On 17 mei 2010, at 06:13, Jeremy Thomerson wrote: >>> >>>> In general, you should not pass references to components to other pages. >>>> That section on anonymous inner classes is telling you that when you >>> create >>>> an anonymous inner class and pass it to another page, you >>>> will inadvertently be passing a reference to the outer class, which is >>>> typically a page. This builds up memory and you will get a OOM. Passing >>>> models between pages is absolutely fine - as long as you're not >>> accidentally >>>> passing a bunch of other stuff with it (including large domain objects - >>>> which should be detached by using a detachable model). The page linked >>> to >>>> even says that you will often pass models between pages. >>>> >>>> -- >>>> Jeremy Thomerson >>>> http://www.wickettraining.com >>>> >>>> >>>> >>>> On Sun, May 16, 2010 at 11:05 PM, Rik van der Kleij < >>> rikvdkl...@gmail.com>wrote: >>>> >>>>> Hi Bernard and Mike, >>>>> >>>>> According to >>>>> >>> https://cwiki.apache.org/WICKET/best-practices-and-gotchas.html#BestPracticesandGotchas-AnonymousInnerclassessharingmodels >>> could eventually lead to Out of memory error. >>>>> >>>>> Holding a page reference in an instance field that points to another >>> page >>>>> looks the same but it is doesn't seems to be a problem. What's the >>>>> difference? >>>>> >>>>> Regards, >>>>> Rik >>>>> >>>>> >>>>> On 16 mei 2010, at 04:39, Michael O'Cleirigh wrote: >>>>> >>>>>> Hello, >>>>>> >>>>>> I'm not sure on the answer to your question about the anonymous inner >>>>> class but in general sharing models between pages can be a bad idea. >>>>>> >>>>>> The memory issues comes into play if the IModel is like Model and the >>>>> contained object is not transient (it is serialized as part of the >>> page). >>>>>> >>>>>> While Pages are serialized each page is serialized independently so on >>>>> page reload the IModel from the first page is no longer the same object >>>>> instance as the IModel from the second page. At deserialization time >>> the >>>>> page1.model.getObject().equals page2.model.getObject() but >>>>> page1.model.getObject() != page2.model.getObject(); so any changes to >>> either >>>>> model are not shared between then. >>>>>> >>>>>> This is not a problem if the model is loadable since the memory of the >>>>> page it is contained in doesn't matter as the value is loaded from the >>>>> backend db or some other independent data source like the httpsession, >>> or >>>>> with wicketApplication. >>>>>> >>>>>> You can see the same effect if you try and share a model between a >>> panel >>>>> and a ModelWindow that uses a PageCreator >>>>>> >>>>>> Hope this helps, >>>>>> >>>>>> Mike >>>>>>> Hi, >>>>>>> >>>>>>> Can someone explain me why it is a memory issue when an instance of an >>>>> anonymous IModel class is passed to another page to be shared, but it >>> seems >>>>> to be no problem when a page reference is passed to another page and is >>> put >>>>> in an instance field (for example to be used in a button to navigate >>> back to >>>>> previous page)? >>>>>>> >>>>>>> Many thanks. >>>>>>> >>>>>>> Regards, >>>>>>> Rik >>>>>>> >>>>>>> >>>>>>> >>>>>>> --------------------------------------------------------------------- >>>>>>> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >>>>>>> For additional commands, e-mail: users-h...@wicket.apache.org >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>> --------------------------------------------------------------------- >>>>>> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >>>>>> For additional commands, e-mail: users-h...@wicket.apache.org >>>>>> >>>>> >>>>> >>>>> --------------------------------------------------------------------- >>>>> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >>>>> For additional commands, e-mail: users-h...@wicket.apache.org >>>>> >>>>> >>> >>> >>> --------------------------------------------------------------------- >>> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >>> For additional commands, e-mail: users-h...@wicket.apache.org >>> >>> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org > For additional commands, e-mail: users-h...@wicket.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org
