[
https://issues.apache.org/jira/browse/WICKET-3789?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13048610#comment-13048610
]
Igor Vaynberg commented on WICKET-3789:
---------------------------------------
i do like this idea as well. it needs to be refined as it is still somewhat
rough. eg i would like to be able to say
for (Foo foo:new ComponentHierarchyIterator<Foo>(page, Foo.class)) without
having to cast to Foo myself
i would also like a new ComponentHierarchyIterator().postOrder()
the part where it gets messier is that it does not separate the configuration
of the visit from the visit so i can say weird stuff like this:
ComponentHierarchyIterator it=new ComponentHierarchyIterator();
for (Component c:it) {
it.filterByClass(Bar.class); <== mutating the visit like that - its strange
to be able to do this
}
in any case, we should put this off until 1.6. 1.5 is stable and we need to
release it asap.
> visitChildren and friends require inner classes. Replace with iterators
> -----------------------------------------------------------------------
>
> Key: WICKET-3789
> URL: https://issues.apache.org/jira/browse/WICKET-3789
> Project: Wicket
> Issue Type: Improvement
> Reporter: Juergen Donnerstag
> Attachments: wicket-3789.patch
>
>
> I never really liked that we need inner classes (implementations of IVisitor)
> for traversing the component hierarchy. When needed, it comes easily to me
> that I need MarkupContainer.visitChildren(), but I always need to look up how
> to use it and friends. Debugging is also more complicated than it has to
> (breakpoint inside the visit function: either another breakpoint behind
> visitChildren or "press the continue-until-end-of-method" key several times
> until you are back). For these reasons I gave Iterators another try. I've
> attached a patch for others to review and provide feedback. I've also added
> test cases (ComponentIteratorTest) and I changed quite some visitChildren
> occassions in core. Maven compiles and successfully executes all tests.
> I put the new classes in org.apache.wicket.util.iterator
> ComponentIterator - An enhanced iterator with filters. Also supports chaining
> iterators. Builder API for class filters, isvisible filters, isenabled
> filters etc. Supports Java for each.
> ComponentHierarchyIterator - enhances ComponentIterator to provide hierarchy
> traversal. Adds traversal filters to separate traversal control from what
> next() returns. Same Builder API. Supports Java for each.
> IteratorFilter - Simple abstract class to implement the filter conditions.
> The Builder API makes use of it to add filters to the iterator.
> Some examples:
> ComponentHierarchyIterator iter = new ComponentHierarchyIterator(page);
> while (iter.hasNext())
> {
> Component component = iter.next();
> }
> for (Component component : new ComponentHierarchyIterator(page))
> {
> }
> new ComponentHierarchyIterator(page)
> .filterLeavesOnly()
> .filterByVisibility()
> .filterByClass(Form.class)
> iter.skipRemainingSiblings(); // skip all remaining component of the same
> parent
> iter.dontGoDeeper() // provided the current component is a container and
> potentially has children, they are ignored
> onEndOfSiblings() is a callback function if you want to be informed about the
> iterator leaving a level
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
