W3C home > Mailing lists > Public > www-style@w3.org > February 2014

Re: [shadow-styling] /shadow vs /shadow-all

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Wed, 19 Feb 2014 09:12:52 -0800
Message-ID: <CAAWBYDCR0Y-aHgh9x8CexO8TWRgQTdJEmnZ0qEgwhi117X5nZQ@mail.gmail.com>
To: fantasai <fantasai.lists@inkedblade.net>
Cc: www-style list <www-style@w3.org>
On Wed, Feb 19, 2014 at 9:05 AM, fantasai <fantasai.lists@inkedblade.net> wrote:
> On 02/10/2014 03:57 PM, Tab Atkins Jr. wrote:
>> The /shadow-all combinator is exactly the older ^ combinator from
>> previous updates.  I added the /shadow combinator (which only selects
>> the top-level elements in the shadow tree) based on suggestions from
>> Boris and Jonas that there should be an easy way to select into a
>> shadow tree without implicitly invoking a descendant combinator, due
>> to the performance implications of descendant combinators.
>>
>> My coworker Elliot pointed out privately, though, that moving only
>> into the top-level elements makes the styling more brittle - if the
>> component author rearranges their shadow DOM so that something isn't a
>> child anymore, it'll break users.
>>
>> He'd prefer that the shortest name go to something that isn't as
>> brittle.  He also pointed out that, with bottom-up selector matching,
>> there's not actually any real cost difference between /shadow and
>> /shadow-all, since you can always cheaply jump from an element in a
>> shadow tree directly up to the shadow host in any reasonable
>> implementation.  (For the same reasons that any element can cheaply
>> jump up to the document in any reasonable implementation.)
>>
>> This seems compelling to me.  I'd like to swap things around to have
>> /shadow be the old ^ combinator, where it selects all the elements in
>> the shadow tree, and either rename the "only top-level elements" one
>> to /shadow-child, or just kill it and rely on use of :top to handle
>> this use-case.
>
>
> I think this really points to a pseudo-element being the better
> way to go. You can use descendant and child combinators as usual
> and don't need to bother with this awkward :top stuff.

This appears to be a non-sequitur.  We're just discussing
shadow-piercing variants of ">" and " ".

~TJ
Received on Wednesday, 19 February 2014 17:13:39 UTC

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