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Re: @else in Media Queries

From: Mark Brown <mark@mercurylang.org>
Date: Fri, 10 Jun 2016 19:53:47 +1000
Message-ID: <CAM4AczD9N7ZU1jGbUuEu8fHsJBjZzsRR_03TZbYL=VsFHzQjDQ@mail.gmail.com>
To: W3C www-style mailing list <www-style@w3.org>
On Fri, Jun 10, 2016 at 6:58 AM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
> On Thu, Jun 9, 2016 at 3:34 AM, Daniel Glazman <daniel.glazman@disruptive-innovations.com> wrote:
>> My recommendation for @else is then the following: yes to @else but
>> we need to have boolean completion in MQs first, to be able to
>> serialize precisely the MQ relevant to a given style rule. That means
>> allowing negated single media features, OR operations and grouping
>> through parentheses. I'm pretty sure we'll have requests for that (if
>> we don't have them yet) anyway.
> We already have all of those.

Well, not quite. Florian's example on the issue tracker [1]
illustrates that you can't always write a separate condition that's
equivalent to an else, because of how unknown media features are

To make the set of operations complete, you could, for example, add a
function such as 'unknown(media-query)' which is true iff its argument
evaluates to unknown. So this doesn't seem a major hurdle.

On Fri, Jun 10, 2016 at 3:34 PM, Daniel Glazman
<daniel.glazman@disruptive-innovations.com> wrote:
> The whole things starts smelling like the worst of hacks in CSS. So an
> editor removing one rule (the @media one) will have to carefully look
> if there is an @else after it. To do what? Remove it? Explode it?

Can you explain how this is different from an editor for any other
language with an if-then-else construct?


[1] https://github.com/w3c/csswg-drafts/issues/112
Received on Friday, 10 June 2016 09:54:16 UTC

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