the way it works makes sense to me...
-igor
On Fri, Aug 26, 2011 at 3:24 PM, Mika Viljanen <mika.vilja...@iki.fi> wrote:
> Hi,
>
> (I was pretty sure I could find an answer to my question by searching
> the list archives and the Wicket Jira, but didn't. But if there's an
> answer somewhere already and I just missed it, I apologize and would
> be very happy if I was pointed to it.)
>
> Is the visitChildren method of MarkupContainer supposed to take into
> account the return value of its IVisitor also if only specific,
> non-container classes are to be visited?
>
> The question naturally makes more sense with an example. Consider this
> simple piece of code:
>
> MarkupContainer container1 = new WebMarkupContainer("container1");
> Label labelA1 = new Label("labelA1", "A1");
> Label labelA2 = new Label("labelA2", "A2");
>
> MarkupContainer container2 = new WebMarkupContainer("container2");
> Label labelB1 = new Label("labelB1", "B1");
> Label labelB2 = new Label("labelB2", "B2");
>
> add(container1);
> container1.add(labelA1, labelA2, container2);
> container2.add(labelB1, labelB2);
>
> container1.visitChildren(Label.class, new IVisitor<Component>() {
> @Override
> public Object component(Component component) {
> System.out.println(component.getDefaultModelObject());
> return CONTINUE_TRAVERSAL_BUT_DONT_GO_DEEPER;
> }
> });
>
> When I wrote the above code I thought the Visitor would only visit
> labels A1 and A2, and it would skip B1 and B2, since they are deeper
> in the object hierarchy and I use the return value
> CONTINUE_TRAVERSAL_BUT_DONT_GO_DEEPER. But the Visitor actually visits
> all four labels anyway. If visitChildren is called without the first
> parameter ("Label.class"), it only visits labels A1 and A2, but also
> container2 (which is what I would expect it to do).
>
> The reason for this is pretty obvious if you look at the source code
> of visitChildren. The traversal depth check depends on the Visitor's
> return value (e.g. CONTINUE_TRAVERSAL or
> CONTINUE_TRAVERSAL_BUT_DONT_GO_DEEPER), and that is set only if no
> specific class was defined (i.e. the first parameter wasn't given and
> all kinds of components are visited) or the class of the component
> matched the given parameter. In this case when visitChildren advances
> to container2, the Visitor isn't called (because only Labels are to be
> visited) and the return value remains null (the default value). And so
> the visiting continues to container2's children, resulting in B1 and
> B2 appearing in the results...
>
> Is this how visitChildren was designed to work? Like I said, I
> expected it to work differently, but the problem might only be in my
> expectations. :)
>
> BR,
> Mika
>
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