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Re: [css21] 'font-family' should disallow 'inherit' in font names more strictly

From: Gérard Talbot <www-style@gtalbot.org>
Date: Tue, 24 Apr 2012 17:55:12 -0400
Message-ID: <7f860998bd0a1d79f500dfc449c20246.squirrel@ed-sh-cp3.entirelydigital.com>
To: "Kang-Hao (Kenny) Lu" <kennyluck@csail.mit.edu>
Cc: "WWW Style" <www-style@w3.org>

Le Mar 24 avril 2012 13:04, Kang-Hao (Kenny) Lu a écrit :
> (12/04/25 0:23), "Gérard Talbot" wrote:
>> Le Mar 24 avril 2012 5:30, Kang-Hao (Kenny) Lu a écrit :
>>> (12/04/24 14:02), John Daggett wrote:
>>>> Tab Atkins Jr. wrote:
>>
>>>>>> The keywords 'initial' and 'default' are reserved for
>>>>>> future use and must also be quoted when used _in_
>>>>>> font names.
>>>>
>>>> This is equally imprecise, it implies that only the keywords are
>>>> quoted when what you mean to say is that font family names
>>>> *containing* these keywords must be quoted.
>>>
>>> Either that or
>>>
>>>   | unquoted global keywords ('inherit', 'initial' and 'default') are
>>>   | not allowed inside <family-name>.
>>
>>
>> div {font-family: inherit;}
>>
>> is allowed, is valid, is permitted and is tested:
>
> Well, I said "inside <family-name>", so if the "Value:" field is
> "<family-name> | inherit", even if 'inherit' doesn't match <family-name>
> because of proposed wording, it still matches the right hand side.
>
> Having said that, since you found this confusing, what about
>
>   | unquoted global keywords ('inherit', 'initial' and 'default') are
>   | not allowed when parsed as <family-name>.
>
> ?
>
>>> I mentioned that I don't like this direction so my propose wording is
>>>
>>>   | If the value of 'font-family' is a single global keyword
>>>   | ('inherit', 'initial' and 'default'), UAs must not interpret it as
>>>   | <family-name> but the meaning of the global keyword.
>>
>>
>> ... unless it is quoted:
>>
>> "
>> Font family names that happen to be the same as a keyword value
>> ('inherit', 'serif', 'sans-serif', 'monospace', 'fantasy', and
>> 'cursive')
>> must be quoted to prevent confusion with the keywords with the same
>> names.
>> "
>> http://www.w3.org/TR/CSS21/fonts.html#font-family-prop
>>
>>
>>> The implication is that 'font-family: foo, inherit' is still valid.
>>> This
>>> follows IE9.
>>
>>
>> div#a {font-family: foo, inherit;} /*  is invalid */
>>
>> div#b {font-family: inherit, bar;} /* is invalid */
>
> Well, this is still questionable before we make a decision


I sincerly do not see a need to fix anything in CSS 2.1, section 15.3 with
regards to this particular matter.


> and this is
> the subject of this thread.



The initial post started with:

Right now, 2.1 says the following about using 'inherit' in a font name:

# The keywords 'initial' and 'default' are reserved for
# future use and must also be quoted when used as
# font names.


"in" is not "as" and quotation was apparently targeted on the font family
names *containing* such keywords.

Anyway,.. I really do not see the need to change anything in CSS 2.1,
section 15.3 with regards to this precise matter.

>
>> The CSS validator also reports these as errors:
>>
>> 1 	div#a 	Value Error : font-family Too many values or values are not
>> recognized : foo,inherit
>> 3 	div#b 	Value Error : font-family Too many values or values are not
>> recognized : inherit,bar
>
> For what it's worth, 'font-family: inherit xx;' (but not 'font-family:
> xx inherit;') is treated invalid by the validator


I will later create+file a bug report on this then.


> and this is different
> from all other browsers. I am reluctant to make yet another summary
> table but we have four behaviors: 1)IE 2) Opera=your reading of the
> current spec 3) WebKit=Firefox 4)W3C CSS Validator.


I created a test on your posted message

{

1a. 'font-family: xxx inherit;' is valid in all browsers
1b. 'font-family: inherit xx;' is valid in IE9 and Opera12alpha but not
others
1c. 'font-family: xxx, inherit;' is valid in all browsers except
Opera12alpha
1d. 'font-family: inherit, xxx;' is valid in IE9

}

and based on Tab's chunk of code.


>
>> Value:  	[[ <family-name> | <generic-family> ] [, <family-name>|
>> <generic-family>]* ] | inherit
>>
>> "
>> A bar (|) separates two or more alternatives: exactly one of them must
>> occur.
>> (...)
>> Brackets ([ ]) are for grouping.
>> (...)
>> An asterisk (*) indicates that the preceding type, word, or group occurs
>> zero or more times.
>> "
>> http://www.w3.org/TR/CSS21/about.html#value-defs
>
> Well, if a keyword 'inherit' can be parsed as <family-name> (the spec
> currently doesn't say it can't), 'foo, inherit' can be parsed as
> "<family-name> , <family-name>" and this is matching the left hand side
> of the grammar.


'foo, inherit' is not parsed as "<family-name> , <family-name>"


'foo, "inherit"' is parsed (and should be parsed) as "<family-name> ,
<family-name>"


"
Font family names that happen to be the same as a keyword value
('inherit', 'serif', 'sans-serif', 'monospace', 'fantasy', and
'cursive') must be quoted to prevent confusion with the keywords with the
same names.
"
http://www.w3.org/TR/CSS21/fonts.html#font-family-prop


> The problem is that a single keyword 'inherit' can match both the left
> hand side (parsed as a single <family-name>) and the right hand side.

No. The single keyword 'inherit' can not match both the left hand side and
the right hand side. As far as I understand this.

E.g.:
http://test.csswg.org/suites/css2.1/nightly-unstable/html4/font-family-rule-004.htm

Gérard
-- 
CSS 2.1 Test suite RC6, March 23rd 2011
http://test.csswg.org/suites/css2.1/20110323/html4/toc.html

Contributions to CSS 2.1 test suite
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Received on Tuesday, 24 April 2012 21:55:46 GMT

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