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Re: css3-background: grammar issue

From: Yves Lafon <ylafon@w3.org>
Date: Tue, 23 Feb 2010 05:45:34 -0500 (EST)
To: fantasai <fantasai.lists@inkedblade.net>
cc: Bert Bos <bert@w3.org>, www-style@w3.org
Message-ID: <alpine.DEB.1.10.1002230540500.27407@wnl.j3.bet>
On Mon, 22 Feb 2010, fantasai wrote:

> On 02/17/2010 07:46 AM, Yves Lafon wrote:
>> On Wed, 17 Feb 2010, Bert Bos wrote:
>> 
>>> On Saturday 09 January 2010 09:11:53 Yves Lafon wrote:
>> 
>>>> There are two possible paths for solving this:
>>>> 1/ disallowing bckground to tart with a <bg-size> (there is already a
>>>> rule forbidding <bg-position> after a <bg-size>, so it's in the same
>>>> range).
>>> 
>>> There is no reason to disallow it on syntactical grounds, but one could
>>> argue that it looks confusing. However, I don't think it is a very
>>> strong argument.
>> 
>> Ok, so why is CSS3-background disallowing
>> background: url("foo.png") / 10em black 10em
>> and not
>> background: url("foo.png") 10em black / 10em
>> 
>> There is nothing confusing in those two cases, and the generalisation of
>> the simple rule "/ <bg-size> immediately followed by <bg-position>" into
>> "<bg-position> must not occur before '/ <bg-size>" seems like a strange
>> decision as well. Just saying that 'background' can't start with
>> '/ <bg-size>' is in the same range of text-based constraint.
>
> Hello Yves,
> Based on your comments on the background shorthand syntax and the discussion
> in the CSSWG's last telecon
>  <http://lists.w3.org/Archives/Public/www-style/2010Feb/0163.html>
>
> I propose the following changes:
>
>  - Change the token '/' to the keyword 'as'
>  - Replace
>      # where ?<bg-position>? must occur before ?/ <bg-size>? if both are present.
>    with
>      | where '<bg-position>' must not occur immediately after 'as <bg-size>'
>
> Would this address your concerns?

Replacing '/' by 'as' will indeed help. The second rule was more an 
example that there were "more restrictive than necessary" rules and just 
adding one to forbid '/' being first was not out of the line. But the new 
wording, "must not occur immediately" will make it easier to check anyway, 
so OK for both.
Thanks,

-- 
Baroula que barouleras, au tiéu toujou t'entourneras.

         ~~Yves
Received on Tuesday, 23 February 2010 10:45:35 GMT

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