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Re: [css3-ui] Aligning 'nav-index' with HTML5 tabindex

From: L. David Baron <dbaron@dbaron.org>
Date: Thu, 1 Dec 2011 16:28:50 -0800
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: Tantek Çelik <tantek@cs.stanford.edu>, www-style@w3.org
Message-ID: <20111202002850.GA14592@pickering.dbaron.org>

[ dropping wai-xtech on this subthread, since it's pure CSS geekery ]

On Thursday 2011-12-01 15:30 -0800, Tab Atkins Jr. wrote:
> On Tue, Nov 29, 2011 at 9:50 PM, Tantek Çelik <tantek@cs.stanford.edu> wrote:
> > On Mon, Nov 21, 2011 at 09:23, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
> >> I also note that nav-index commits the cardinal sin of allowing only
> >> non-zero positive <number>s, which means that its range is bounded but
> >> has no minimum value.  This should either allow 0 or allow the full
> >> <number> range.
> >
> > Why?
> 
> Not having a minimum value means we can't do things like setting it to
> its minimum value when attr() results in a number below its range.

Strongly agreed here, by the way.  So far, restrictions on ranges of
allowed values in CSS are all expressable as [1] closed intervals rather
than open intervals [2], and I'd like to keep it that way so that
it's always possible to clamp a possibly-out-of-range value to the
edge of the allowed range, as calc() does.  (I don't see anything in
http://dev.w3.org/csswg/css3-values/#attr saying attr() has that
behavior, though.)

-David

[1] I think there are some that are expressed as open intervals but
    still expressable as closed intervals:  in particular, they were
    expressed as "integers greater than 0" but can be expressed
    alternatively as "integers greater than or equal to 1".

[2] http://en.wikipedia.org/wiki/Interval_%28mathematics%29#Terminology

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                           http://www.mozilla.org/   𝄂
Received on Friday, 2 December 2011 00:29:29 GMT

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