W3C home > Mailing lists > Public > www-style@w3.org > February 2010

Re: [css3-background] grammar issue

From: Brad Kemper <brad.kemper@gmail.com>
Date: Fri, 26 Feb 2010 23:09:54 +0800
Message-Id: <B47D5414-9299-451C-BE01-600C25BA4F6F@gmail.com>
To: Yves Lafon <ylafon@w3.org>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, fantasai <fantasai.lists@inkedblade.net>, Bert Bos <bert@w3.org>, "www-style@w3.org" <www-style@w3.org>

On Feb 26, 2010, at 10:21 PM, Yves Lafon <ylafon@w3.org> wrote:

> On Fri, 26 Feb 2010, Brad Kemper wrote:
>> On Feb 26, 2010, at 4:43 AM, Yves Lafon wrote:
>>>> I disagree. In border-image you can have nothingness between the  
>>>> two slashes.
>>> What?? If that's true (and the grammar seems to allow that,  
>>> unfortunately), then it's really insane, unless 'nothing' is an  
>>> allowed value, but I bet it is not.
>> Why would 'nothing' have to be an allowed value? Leaving out a  
>> value out from a shorthand does not set it to 'nothing', and it  
>> does not change the syntactical rules of the shorthand.
> Yes it does, separators must separate things.
> border-image: // 10px
> (or border-image: / / 10px) is also a bad unless it means
> border-image: <nothing> / <nothing> / 10px
> As <nothing> is not an allowed value,

You didn't say <nothing> would have to be ab allowed value, you said  
'nothing' had to be an allowed value. If <nothing> is defined as an  
empty string or null, then sure it is allowed, as many times as you  
want, in any property you want. Put a million of them between each  
letter if you want, since the end result is the same as if you hadn't.  
I think it is ridiculous to say that a shorthand property needs to  
explicitly allow for the non-typing of nonexistant text.

> something else than '/' ou ',' (defined as separators) should be  
> used, unless you add specific rules like "don't start with a / and  
> don't put two / in a row", or even add an 'ignored' value.

That doesn't make any sense. Add an emprty string or not, the result  
is the same. You don't ever need grammar to say that what isn't there  
should be ignored. And I see absolutely no reason to unnecessarily  
restrict authors  with rules like "don't start with a / and don't put  
two / in a row".

The slashes are easy to distinguish as separators, whether separating  
two possibly confused values in the background shorthand, or groups of  
values more restrictively in border-image. Once you learn what is  
allowed or not on the two sides of each slash (a very simple thing to  
learn and remember), then it helps make the otherwise complex  
shorthand easy to read.
Received on Friday, 26 February 2010 15:10:41 UTC

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