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Re: [css-logical-props] do shorthands have logical component longhands?

From: L. David Baron <dbaron@dbaron.org>
Date: Sat, 20 Dec 2014 16:33:56 -0500
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: Cameron McCormack <cam@mcc.id.au>, www-style list <www-style@w3.org>
Message-ID: <20141220213356.GA25674@crum.dbaron.org>
On Thursday 2014-12-18 16:46 -0800, Tab Atkins Jr. wrote:
> There's an issue in the spec about whether the physical/logical
> versions of the shorthands also reset the logical/physical properties.
> 
> fantasai says they definitely should be reset by the shorthand.

If we want them to, then we need to introduce two new concepts:
 * the concept that the order in which a shorthands longhands occur
   is relevant
 * the concept that a shorthand can generate its longhands in
   different orders depending on the value

If we don't want them to, we need to introduce one new concept:
 * a shorthand that generates different longhands in specified
   value space depending on what was specified (even though it
   always changes the same set of computed values)
(This means relaxing the invariant that a shorthand always
*specifies* the same set of properties to the invariant that it
always specifies properties that change the computed values of the
same set of properties, and that they shouldn't be reset by the
shorthand.)

Having the shorthand only generate the relevant properties (either
the logical ones or the physical ones, but not both) feels more
sensible to me, so I'm inclined to go in that direction, even though
it might be a little more difficult implementation-wise.  (I think
it's probably simpler to do the two new concepts listed first than
the one new concept listed afterwards.)  But I guess I don't feel
that strongly.

(That said, I don't think this relates to what we're likely to
implement in the near future, which is probably only the minimum
needed to have working logical properties.  We probably want to
ensure the spec is more stable before implementing the 'logical'
keyword on shorthands.)

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)

Received on Saturday, 20 December 2014 22:43:46 UTC

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