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Re: Selectors 4 and Variables

From: Brian Kardell <bkardell@gmail.com>
Date: Sat, 1 Oct 2011 10:15:13 -0400
Message-ID: <CADC=+jfj9yH5ffYtZ0N2e8kdC760rhGg-+_C2JJSpcbw7Vg1Fg@mail.gmail.com>
To: François REMY <fremycompany_pub@yahoo.fr>
Cc: www-style@w3.org, fantasai <fantasai.lists@inkedblade.net>
Is it just me or does this seem highly related to the :scope / :matches /
@global discussion a few days (maybe a week) back?
On Oct 1, 2011 4:09 AM, "François REMY" <fremycompany_pub@yahoo.fr> wrote:
> We can use the :has pseudo class and restricts his usage to achieve the
same
> thing. Those allowed usages can then be extended over time, in function of

> what implementers are ready to do.
>
> It seems clear to me that the goal of the "$" notation was to force the
> ":has" to be at the last position of the selector. This allows to restrict

> the needed changes in the rule-matching algorithm to : "Allow a selector
> matching an element to have effect on his ancestrors". This mean the only
> restriction added to the system is that we should start to match CSS rules

> to the deepest point of the DOM Tree and go backward, which most UA
probably
> do by now. If we allow :has everywhere, this assumption fails to be proven

> and we may need a more complex tooling to find matched elements for those
> rules, probably iterating two or more times the rule-matching algorithm
each
> time a new "parent match" is found.
>
> It may seems reasonable to restrict the :has pseudo-class to the last
> position of the selector. It achieves the same effect and it's easy to add

> more possibilities in the future without changing the syntax.
>
> (Or maybe am I missing the point?)
>
>
> -----Message d'origine-----
> From: fantasai
> Sent: Saturday, October 01, 2011 5:15 AM
> To: www-style@w3.org
> Subject: Re: Selectors 4 and Variables
>
> On 09/30/2011 05:03 PM, Tab Atkins Jr. wrote:
>>
>> I thought it was generally agreed long ago that the best approach was
>> to use :has() rather than a marker in the selector. It's more general
>> and allows more types of things to be expressed.
>
> It wasn't *generally* agreed. It was only agreed by some people.
>
>> Basically, the subject indicator is exactly equivalent to a :has()
>> pseudo limited to the end of the selector:
>>
>> foo $bar baz {...} == foo bar:has(baz) {...}
>>
>> However, :has() can be placed anywhere in the selector, and so allows
>> more powerful selections:
>>
>> label:has(:checked) + section> p {...}
>
> The limitation to a single branch here is intentional, due to
> implementation concerns.
>
> If I were going to do branching, I'd expand :matches() to take full
> selectors rather than only compounds.
>
> label:matches(!#$%? :checked) + section > p { ... }
>
> This has the advantage that selectors work the same whether they
> are within or without the pseudo-class argument. There's neither
> implicit nor dangling combinators, as you have with :has().
>
> ~fantasai
>
>
Received on Saturday, 1 October 2011 14:15:40 GMT

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