// Component is removed
component.setParent(null);
But ofcourse this could not be the case that the component itself is not removed but a parent of it and he is reused instead of its parent.
But this is pretty far fetched don't think this will happen a lot.
I just checked in the code where i just remove the component first if he still has a parent.
johan
On 12/22/05, Juergen Donnerstag <[EMAIL PROTECTED]> wrote:
You mentioned that throwing an exception won't work because if
Components are moved around (for whatever reason), the
markupContainer.parent could already be set. IMO Wicket should do
markupContainer.parent = null whenever we remove a Component from the
hierarchy and that happens in markupContainer.remove(Component) and
replace(Component). If we make sure parent == null, than we are able
to throw an exception and IMO that is the better option.
Juergen
On 12/22/05, Johan Compagner <[EMAIL PROTECTED]> wrote:
> remove the parent reference? That already happens because we set an other
> parent ofcourse.
> But just do it as swing does this is swing/awt code:
>
> /* Reparent the component and tidy up the tree's state. */
> if ( comp.parent != null) {
> comp.parent.remove(comp);
>
> So that is exactly what i did type. Then we don't have any problems of
> duplicate childs.
>
> johan
>
>
>
> On 12/22/05, Juergen Donnerstag < [EMAIL PROTECTED]> wrote:
> >
> > > I don't think we can check if the component already has a parent and
> then just throw an
> > > exception.. Because it could be reusing components/panels and he wants
> to move if
> > > from X to Y
> >
> > And if we do parent = null during remove() and replace()?
> >
> > If we can not throw an exception, than add() is more like addOrMove(),
> > correct. Though it avoids the problem of having 2+ equal Component
> > objects in the hierarchy, I predict that users will still fall into
> > the trap and open bug reports. We will than close it with a comment
> > referring to the javadoc and we'll than do it a couple of times until
> > we evaluate a "better" solution.
> >
> > Indepent on how we decide, IMO we should make your change anyway.
> >
> > If removing the parent while removing the Component hierarchy does not
> > work. Another approach could be a transient map added to Page and each
> > object is put into it with its hashcode (kind of flattened tree). It
> > is fast and very easy to implement. And we do not need additonal
> > memory except for the HashMap. The components are already kept with
> > the hierarchy anyway. And because it is transient, it won't be
> > serialized. To rebuild the HashMap in case of a server switch in a
> > cluster is easy as well. What about this approach? But I'd still
> > prefer to remove the parent reference from the Component.
> >
> > Juergen
> >
> > On 12/22/05, Igor Vaynberg < [EMAIL PROTECTED]> wrote:
> > > that sounds good to me. it is something we need to have clearly
> documented
> > > in the add() function though.
> > >
> > > -Igor
> > >
> > >
> > >
> > > On 12/21/05, Johan Compagner < [EMAIL PROTECTED]> wrote:
> > > > Why don't we just do it as swing does?
> > > >
> > > > Check if the component already has a parent. And remove it from the
> parent
> > > first and then add it to yourself.
> > > >
> > > > I don't think we can check if the component already has a parent and
> then
> > > just throw an exception.. Because it could be reusing components/panels
> and
> > > he wants to move if from X to Y
> > > >
> > > > something like this in MarkupContainer:
> > > >
> > > > private final void addedComponent(final Component component)
> > > > {
> > > > // Check for degenerate case
> > > > if (component == this)
> > > > {
> > > > throw new
> IllegalArgumentException("Component
> > > can't be added to itself");
> > > > }
> > > > <NEW>
> > > > // remove if from another parent.
> > > > MarkupContainer mc = component.getParent();
> > > > if(mc != null)
> > > > {
> > > > mc.remove(component);
> > > > }
> > > > else if(mc == this)
> > > > {
> > > > // component already added don't do anything
> > > > return;
> > > > }
> > > > </NEW>
> > > > // Set child's parent
> > > > component.setParent(this);
> > > >
> > > > // Tell the page a component was added
> > > > final Page page = findPage();
> > > > if (page != null)
> > > > {
> > > > page.componentAdded(component);
> > > > }
> > > > }
> > > >
> > > >
> > > > johan
> > > >
> > > >
> > > >
> > > >
> > > > On 12/22/05, Igor Vaynberg < [EMAIL PROTECTED]> wrote:
> > > > > what do you think about performance? seems kind of overkill to
> traverse
> > > the entire tree every time you add a component, especially for
> > > listview/dataview type stuff. i know it wont be a problem in prod
> because
> > > component-use-check should be turned off, but still in development it
> might
> > > be a pain.
> > > > >
> > > > > i think maybe this one we call user error and leave it at that?
> > > > >
> > > > > -Igor
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > On 12/21/05, Juergen Donnerstag < [EMAIL PROTECTED] >
> wrote:
> > > > > > We do not check that a component (same object instance) is added
> twice
> > > > > > at different levels in the hierarchy.
> > > > > >
> > > > > > This test could be added to MarkupContainer.add() though.
> Something
> > > like
> > > > > >
> > > > > > // Check that the same component instance is not
> > > > > > // added more than once.
> > > > > > if
> > > (getApplicationSettings().getComponentUseCheck())
> > > > > > {
> > > > > > Page page = findPage();
> > > > > > if (page != null)
> > > > > > {
> > > > > >
> > > page.visitChildren(new IVisitor()
> > > > > > {
> > > > > >
> > > public Object component(Component component)
> > > > > > {
> > > > > >
> > > if (component.equals(child))
> > > > > >
> > > {
> > > > > >
> > > throw new WicketRuntimeException(
> > > > > >
> > > "You can not add the same
> > > Component twice: "
> > > > > >
> > > + child.toString());
> > > > > >
> > > }
> > > > > >
> > > return IVisitor.CONTINUE_TRAVERSAL;
> > > > > > }
> > > > > > });
> > > > > > }
> > > > > > }
> > > > > >
> > > > > >
> > > > > > It seems to work. Any objections?
> > > > > >
> > > > > > Juergen
> > > > > >
> > > > > > On 12/21/05, Juergen Donnerstag < [EMAIL PROTECTED]>
> wrote:
> > > > > > > On 12/21/05, Igor Vaynberg < [EMAIL PROTECTED] > wrote:
> > > > > > > > hi Juergen,
> > > > > > > > could you please take a look at
> > > > > > > >
> > > > > > > > Bugs item #1375584, was opened at 2005-12-07 18:44
> > > > > > > > Message generated for change (Comment added) made by ivaynberg
> > > > > > > > You can respond by visiting:
> > > > > > > >
> > >
> https://sourceforge.net/tracker/?func=detail&atid=684975&aid=1375584&group_id=119783
> > > > > > > >
> > > > > > > > i think this is more your area then mine. this guy added the
> same
> > > component
> > > > > > > > to the page twice. once to a form and once to a feedbackborder
> > > which was
> > > > > > > > also added to the form. wicket didnt catch this.
> > > > > > > >
> > > > > > >
> > > > > > > I'll check it.
> > > > > > >
> > > > > > > Juergen
> > > > > > >
> > > > > >
> > > > > >
> > > > > >
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