W3C home > Mailing lists > Public > www-style@w3.org > February 2011

Re: CSS Variables Draft Proposal

From: Linss, Peter <peter.linss@hp.com>
Date: Fri, 11 Feb 2011 03:10:48 +0000
To: Tab Atkins Jr. <jackalmage@gmail.com>, Daniel Glazman <daniel.glazman@disruptive-innovations.com>
CC: www-style list <www-style@w3.org>
Message-ID: <C979E5A8.4A61%peter.linss@hp.com>
On 2/10/11 5:53 PM, "Tab Atkins Jr." <jackalmage@gmail.com> wrote:

>On Thu, Feb 10, 2011 at 5:34 PM, Daniel Glazman
><daniel.glazman@disruptive-innovations.com> wrote:
>> Le 11/02/11 02:15, Linss, Peter a écrit :
>>
>>> Don¹t forget this case:
>>> @var $foo /*this_is_a_valid_url*/;  p { content: url($foo); }
>>>
>>> Is it a comment or not?
>>
>>
>> Never. A comment is explicitely said to be able to happen anywhere
>> between tokens in the grammar and you can almost consider it's
>> stripped before tokenization (even if of course it is not).
>>
>> The variable assignment above is always reduced to @var $foo ;
>
>Exactly.  Which is a parse-time error anyway, making the declaration
>invalid.

Invalid declaration or variable with an invalid (or null) value? IOW, does
a @var object show up in the CSSOM for the stylesheet that could have a
value assigned later?

Also note that:
@var $foo /*something*/else; p { content: url($foo); }

would be perfectly valid, but would evaluate to:
p { content: url(else); }

while authors may very well expect to get:
p { content: url(/*something*/else); }

which is a valid url: "/*something*/else".

At the very least, you should add a note stating that values for variables
intended to  be used inside url() should be quoted strings.

-----

Actually, strike that. I forgot that $ is perfectly legal inside a url, so:
p { content: url($foo); }

Should NOT expand the variable, as it should be seen as a single url()
token with the url value of "$foo". "(" and ")" are also legal inside a
url, so:
p { content: url(var(foo)); }
would be a url with the value "var(foo)", not the expansion of $foo either.

So add a note that variables don't work at all inside url(). You'd need to
use:
@var $foo url(...);

Unless you want to come up with another variable syntax that isn't legal
in a url (but probably best not to).
Received on Friday, 11 February 2011 03:12:01 GMT

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