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Re: Proposal for limited :matches pseudoclass

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Thu, 31 Jul 2008 16:19:41 -0700
Message-ID: <4892488D.9010105@mit.edu>
To: Simetrical <simetrical@gmail.com>
CC: www-style list <www-style@w3.org>

Simetrical wrote:
> From Boris' last post, I guess the answer to this is that it's a good
> deal more complex, although maybe manageably.  Every time an element
> is added, you might need to recompute style for its immediately
> preceding sibling.  Of course, if you recompute style for an element
> and it turns out that some inheritable property has changed value, you
> need to recompute style for all its descendants, which could be a lot.
>  On the other hand, "foo + bar" recomputes nothing at all.

On appends, that's correct.  On other mutations, it has to recompute if 
you put a <foo> in.

> "foo:matches(~ bar)" would be worse, because it would require
> recomputing style for all preceding siblings.

 > And "foo:matches( bar)" would be worst of all, because
> it could require recomputing style for all *ancestors*, which would
> include the root element, and therefore *all* elements.

Indeed, modulo some sort of optimization setup.

> Am I approximately right here?

If I understand the :matches() proposal, yes.

-Boris
Received on Thursday, 31 July 2008 23:20:26 GMT

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