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Re: Proposal for "Cascading Attribute Sheets" - like CSS, but for attributes!

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 21 Aug 2012 14:26:27 -0700
Message-ID: <CAAWBYDBQ4XEsqmULpCMf=oTE95ouJ6e6dRPgR6MrXDxP-dVFrA@mail.gmail.com>
To: Travis Leithead <travis.leithead@microsoft.com>
Cc: Ojan Vafai <ojan@chromium.org>, public-webapps <public-webapps@w3.org>
On Tue, Aug 21, 2012 at 2:20 PM, Travis Leithead
<travis.leithead@microsoft.com> wrote:
>> From: Tab Atkins Jr. [mailto:jackalmage@gmail.com]
>> On Tue, Aug 21, 2012 at 1:42 PM, Ojan Vafai <ojan@chromium.org> wrote:
>> > On Tue, Aug 21, 2012 at 1:01 PM, Tab Atkins Jr. <jackalmage@gmail.com>
>> > wrote:
>> >> On Tue, Aug 21, 2012 at 12:37 PM, Ojan Vafai <ojan@chromium.org>
>> wrote:
>> >> > Meh. I think this loses most of the "CSS is so much more convenient"
>> >> > benefits. It's mainly the fact that you don't have to worry about
>> >> > whether the nodes exist yet that makes CSS more convenient.
>> >>
>> >> Note that this benefit is preserved.  Moving or inserting an element
>> >> in the DOM should apply CAS to it.
>> >>
>> >> The only thing we're really losing in the dynamic-ness is that other
>> >> types of mutations to the DOM don't change what CAS does, and some of
>> >> the dynamic selectors like :hover don't do anything.
>> >
>> >
>> > Ah, I missed the "plus a mutation observer that reruns the mutations
>> > on any nodes added to the document" bit. Ok, so this timing is very specific
>> then.
>> > It would get applied at the microtask time, not at the time the DOM
>> > was modified. Would it get applied before or after mutation observers
>> > get called? Seems like you'd want it to execute first. Calling it
>> > after mutation observers would require an extra delivery of mutations
>> > after the attributes are applied, which seems silly.
>>
>> I presume there's an ordering of mutation observers, such that ones defined
>> earlier in document history get the notifications first, or somesuch?  If so,
>> CAS should indeed run before any author-defined observers.
>
> So this can basically be completely authored as a script library using existing or soon-to-be-implemented technologies? You just need a CAS JS parser, CAS JS rule engine, and mutation observers? Tab, you should just supply an implementation of this. :)

I could, yes.  ^_^  However, "you can just do it as a library" isn't
an argument against adding a feature to the platform, if the feature
is sufficiently useful.

~TJ
Received on Tuesday, 21 August 2012 21:27:26 GMT

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