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Re: [css21][css3-cascade] Proposal for value assignment to shorthand properties

From: Anton Prowse <prowse@moonhenge.net>
Date: Wed, 11 Jan 2012 22:08:55 +0100
Message-ID: <4F0DFA67.5020901@moonhenge.net>
To: www-style@w3.org
On 11/01/2012 20:53, Bjoern Hoehrmann wrote:
> * Anton Prowse wrote:
>> Interesting.  So 'font' went from being an active shorthand to a passive
>> one.  In my proposal, I think that would be forbidden.  (This particular
>> example isn't a practical problem, though, since several UAs don't treat
>> any shorthands as active at the moment so we can just treat 'font' as if
>> it were always a passive shorthand.
>>
>> Are you aware of any other examples like this?
>
> Well `border` resets `border-image`, but you will have to create a list
> on your own.
>
>>> A shorthand set to either of the values results in setting all the sub-
>>> properties to the same value plus whatever else is required, like re-
>>> setting certain other properties. This should be clear from the syntax
>>> of the shorthand properties, where `inherit` is only allowed as alter-
>>> native for everything else (and the references to longhands do not in-
>>> clude `inherit` as explained in the definition of the notation), but in
>>> CSS 2.1 C.3.1 this is more explicit.
>>
>> Indeed; I don't think I contradicted that, although I did query in a
>> recent thread[1] with Tab what the exact reasons were for this
>> all-or-nothing approach but it hasn't yet received a response.  (I
>> suspect the answer will turn out to be rather influential to any
>> proposal for fixing shorthands.)  Also, the "whatever else is required"
>> is interesting.  By "resetting certain other properties" I guess you're
>> referring to 'font-stretch' in your 'font' example above.  Did you have
>> any other cases in mind?
>
> I am not sure which rationale you are looking for. As for the latter,
> the point is that the CSS Working Group has not made any promises on
> how future shorthand properties will be defined, and the CSS Working
> Group isn't good at keeping promises where it does make them, see the
> ever-changing never-changing core syntax, so any "model" for short-
> hand properties would have to be open-ended, or it would have to be
> made clear that the "model" introduces constraints for future short-
> hands. Currently I am not aware of side-effects beyond those mentioned.

OK.  Thanks for the input!

Cheers,
Anton Prowse
http://dev.moonhenge.net
Received on Wednesday, 11 January 2012 21:12:27 GMT

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