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Re: ::distributed and relative selectors (Was Re: [shadowdom]: Using :root to specify the insertion point in ::distributed)

From: fantasai <fantasai.lists@inkedblade.net>
Date: Fri, 19 Apr 2013 00:12:41 -0700
Message-ID: <5170EE69.2030205@inkedblade.net>
To: www-style@w3.org
On 04/18/2013 05:27 PM, Hayato Ito wrote:
> On Fri, Apr 19, 2013 at 2:44 AM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
>> On Thu, Apr 18, 2013 at 1:44 AM, Hayato Ito <hayato@google.com> wrote:
>>> The subject was changed.
>>> On Wed, Apr 3, 2013 at 9:01 AM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
>>>> On Tue, Apr 2, 2013 at 3:01 PM, Dimitri Glazkov <dglazkov@google.com> wrote:
>>>>> Using scope-relative approach (which I love), what does
>>>>> ::distributed(:scope) represent?
>>>>
>>>> Nothing.  The scope element is a theoretical construct here
>>>> representing a container for all the distributed elements, not a real
>>>> element that you can do something with.
>>>
>>> I am now implementing relative selectors in blink.
>>> As the first usecase of relative selectors, I've tried to use it in
>>> '::distributed(..)' pseudo elements.
>>>
>>> Now I have a question. Let me use the following deduction:
>>>
>>> 1). content::distributed(> .hello)               ->  Please assume this matches.
>>> 2). content::distributed(:scope > .hello)        -> Matches. (1 and 2
>>> should be equivalent acccording to the defintion of relative
>>> selectors).
>>> 3). content::distributed(*:scope > .hello)       -> Matches.
>>> 4). content::distributed(content:scope > .hello) -> Matches.
>>> 5). content::distributed(content > .hello)       -> Should not match.
>>
>> I think that, for the purpose of ::distributed, the scope element
>> should be an abstract container, not the actual <content> element.
>> This container would act as an element for the purposes of selectors,
>> but it has no tagname or any other quality to select on.  So, #1, #2,
>> and #3 would match, but #4 and #5 wouldn't, because the scoping
>> element isn't named "content".
>
> I noticed that we don't need 4) and 5) to prove contradiction. See the
> following example, introducing 4':
>
> 1). content::distributed(> .hello)               ->  Please assume this matches.
> 2). content::distributed(:scope > .hello)        -> Matches. (1 and 2
> should be equivalent according to the defintion of relative
> selectors).
> 3). content::distributed(*:scope > .hello)       -> Matches.
> 4'). content::distributed(* > .hello)       -> Should not match.
>
> 3) matches, but 4') should not match.
>
> I think it is hard to justify using :scope in this context. I am
> afraid that we should handle ':scope' in this context very *tricky* in
> implementing this. Maybe the spec is wrong.
> My proposal is using ':root' as suggested in the original thread.

I don't see how using :root solves the problem any more than disallowing
:scope. If there's no reason for :scope to be part of this syntax, let's
just say it matches nothing.

~fantasai
Received on Friday, 19 April 2013 07:13:34 UTC

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