[webkit-dev] attached()

[Eric Seidel]

On Thu, Sep 9, 2010 at 12:43 AM, Maciej Stachowiak <mjs at apple.com> wrote:
>
> On Sep 9, 2010, at 12:00 AM, Eric Seidel wrote:
>
>> I'm about to remove the last non-lazy attaching element.
>> https://bugs.webkit.org/show_bug.cgi?id=45365
>>
>>
>> I think we can now kill the whole concept of being "attached".
>>
>> attached() does not necessarily mean you have a renderer.  It just
>> means that something called attach() or lazyAttach() on you.
>>
>>
>> Instead, we could change all elements to mark themselves (and their
>> parents) as needing style recalc during insertedIntoDocument(),
>> effectively "attaching/lazyAttaching".
>
> Presumably they should mark their parents as "child needs style recalc", not needing recalc themselves.

Turns out they also have to mark themselves as needing recalc.  I
tried only marking the parents in this latest patch and failed. :)
http://trac.webkit.org/browser/trunk/WebCore/dom/Node.cpp#L759

>>
>> (We could also fix the current lazyAttach() code to check to see if a
>> parent is already marked with a child needing style resolve, and stop
>> walking to prevent N^2 behavior.)
>>
>> I'm not sure if it would make sense to keep the "attached" flag around
>> to make sure the attach logic is never run twice.
>
> Do any attach() methods still do nontrivial work? Is it an error to call it twice, or not properly paired up with detach()?

I haven't done a full survey of attach() yet, but yes, many elements
override attach.

It is an error to call attach() twice:
http://trac.webkit.org/browser/trunk/WebCore/dom/Node.cpp#L1191