Thanks Joel,
I think I understand you but let me overview my situation and fire
some questions.
My situation is legal situation I think:
I have a man part of the page that I want to use to show some static
information. There for I put the main page aside like explained above
and add the HTML text widget that is then shown. The user then simple
toggles between the two.
The main page is a RootPanel and contain two other RootPanels: a login
html part and some dynamic hyperlink part.
It's setup like this as I don't want to construct the whole page with
GWT, as the GWT part's on the main page (the user sees when he starts)
is only small, and as such that the user has already something to look
at. And the design of the page can be done outside of gwt in this way.
Anyway, if I understand you correctly I have to call detachNow on the
2 Rootpanels when switching to static information, or not ? And when
the user is switching back, I should reattach them again? How do I
this is latter one as I can only detach widgets in the RootPanel and
the method onAttach is protected ? :(
If I don't do this I will get the assertion exception when the user
clicks refresh when looking at the static information.
Any way how to do this, because when I am switching, I have no idea
which RootPanels should be detached :(....
Idea: shouldn't be possible to attach the main RootPanel (that
contains the other root panel) somewhere in the DOM temporeraly when
switching tot the static content, such a way that it isn't visible,
but that it complies to your requirements above. Then when the user
switches back to the main content, I place back the main RootPanel in
the DOM where it was located, such that it will be automatically
removed from his temporeraly DOM location ?
Please some advice on this? and maybe where to place it on the dom?
-- Ed
On Sep 24, 3:40 pm, "Joel Webber" <[EMAIL PROTECTED]> wrote:
> To reiterate:
> - RootPanel.detachOnWindowClose() must be called for all widgets that "have
> no parents".
> - This is implicitly called by Widgets' wrap() methods and
> RootPanel.get(id).
> - All widgets for which this method is called will remain marked as
> 'attached' until RootPanel.detachNow() is called.
> - If a widget attached in this way has its element detached from the DOM,
> implicitly or explicitly, you *must* call RootPanel.detachNow().
> - There is no way for GWT to know that you've done this, because the
> browser doesn't provide this notification.
> - If the assertion in RootPanel.detachWidgets() fails, that means that a
> widget was found in the detach list that is *not* attached to the DOM. This
> proves that the element was detached without its Widget being passed to
> RootPanel.detachNow().
>
> This code cannot realistically know about your DOM structure, so if you do
> something like this:
>
> <div id='outer'>
> <button id='inner'/>
> </>
>
> html = HTML.wrap(Document.get().getElementById("outer"));
> button = Button.wrap(Document.get().getElementById("inner"));
> html.setInnerHTML("Look, I just nuked the button widget!");
>
> You still have to call detachNow() for the inner button widget. Despite the
> fact that the outer HTML widget appears to contain the Button widget,
> there's still no parent-child hierarchy at the widget level.
>
> Honestly, I would prefer to assert up front that this sort of implicit
> parent-child relationship among 'root' widgets not be created in the first
> place, but that's pretty tricky, and I don't believe it could be resilient
> to arbitrary DOM trickery anyway.
>
> Cheers,
> joel.
>
> On Tue, Sep 23, 2008 at 10:32 AM, Ed <[EMAIL PROTECTED]> wrote:
>
> > Thanks again for your answer.
>
> > Let me see if I understand you completely.
>
> > > If you are going to be removing existing RootPanels from the DOM
> > implicitly
> > > (i.e. by removing one of their parent elements), you're going to have to
> > > call RootPanel.detachNow() on them.
>
> > By removing you mean, physical removing it from the DOM without
> > detaching it?
>
> > Calling "widget.onDetach()" is enough for overcoming this orphan
> > problems?
>
> > Is so, why does the assertion not take that into account? I mean, in
> > my case I switch the original content for some other HTML widget,
> > like:
> > stuff.clear();
> > stuff.add(otherWidget);
>
> > In the clear() method it will remove the HTML widget that contains the
> > RootPanels, such that it will properly detach all his children and as
> > such the RootPanels. Shouldn't a RootPanel override the onDetach()
> > method and then remove itself form the widgetsToDetach list? Isn't
> > this what happens when calling RootPanel.detachNow(theRootPanel)? such
> > that it can be automatically done in the onDetach() method in
> > RootPanel.
>
> > I think I am missing something :(.. Please some more details if
> > possible, or a tinny example?
>
> > I understand that a Widget should be attached to the Document body to
> > be removed properly, but I don't understand the Assertion. Even do
> > you signal in the Assertion that he isn't attached to the Body, you
> > are calling onDetach() anyway, so I would say it's not important
> > anymore, he is properly detached anyway (just like what happens in
> > RootPanel.detachNow() ), so what's the point of this Assertion? :(
>
> > -- Ed
>
> > On Sep 23, 3:33 pm, "Joel Webber" <[EMAIL PROTECTED]> wrote:
> > > If you are going to be removing existing RootPanels from the DOM
> > implicitly
> > > (i.e. by removing one of their parent elements), you're going to have to
> > > call RootPanel.detachNow() on them. The reason this is necessary is that
> > > otherwise they will be "orphaned", meaning that they're out of the DOM,
> > but
> > > neither they nor their child widgets are aware of having been removed.
> > This
> > > can break a number of things, including potentially creating leaks.
> > That's
> > > also why the assertion in detachWidgets() is necessary -- I would prefer
> > to
> > > be able to throw an exception when the problem is created (i.e. when the
> > > parent element is removed from the DOM), but there's no way to receive
> > > notification of this.
>
> > > On Mon, Sep 22, 2008 at 4:57 PM, Ed <[EMAIL PROTECTED]> wrote:
>
> > > > He Joel,
>
> > > > Just a tinny problem I am still stuck with:
> > > > In your example above, the replaced content, contains a few more
> > > > RootPanels like this:
> > > > ...>
> > > > <div id='stuff'>
> > > > <... stuff ...>
> > > > <div id='rootPanela'>
> > > > ....
> > > > <div id='rootPanelb'>
> > > > </div>
> > > > <...>
>
> > > > What I do: replacing the content of id="stuff" with some HTML widget
> > > > when the user presses a button, like you describe above. When the user
> > > > clicks another button, I put back the original content.
> > > > However, the original content contains some html snippets that are
> > > > loaded with a RootPanel (for example to add some Form).
> > > > If the user clicks a button such that the original content is
> > > > replaced, such that the RootPanels are put aside and not attached to
> > > > the body, the new code (I think it's even your code ;)) in RootPanel:
> > > > detachWidgets will throw an Assert exception when the hosted browser
> > > > is refreshed at that moment, as these Rootpanels aren't attached to
> > > > the Body and the RootPanel will try to remove it when the window
> > > > closes.
>
> > > > Any idea how to solve this?
> > > > I could remove these RootPanels from the widgetsToDetach in the
> > > > RootPanel when they are put aside, but I don't know the exact
> > > > RootPanel beforehand and I don't like this solution as it avoids my
> > > > code from being losely coupled...
>
> > > > Is this exception realy a possible memory leak? And might it not a bit
> > > > too tight (the exception)
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