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Re: [css3-mediaquery] Clarification of 'not'

From: Håkon Wium Lie <howcome@opera.com>
Date: Wed, 9 Jan 2008 18:09:27 +0100
Message-ID: <18308.65479.820857.967010@gargle.gargle.HOWL>
To: "Anne van Kesteren" <annevk@opera.com>
Cc: fantasai <fantasai.lists@inkedblade.net>, www-style@w3.org

Also sprach Anne van Kesteren:

 > >> I think it's a terrible idea. @media not 3d-glasses should be false.
 > >> We don't *know* whether this device would match a future 3d-glasses
 > >> query or not.
 > >
 > > True. But we say that queries involving unknown media types should be
 > > false. E.g.:
 > >
 > >   @media 3d-glasses { ... }
 > >
 > > I assume we all agree that this should be false.
 > >
 > > Logically, it follows that "not false" is true.
 > >
 > > I think this is an edge case that will not cause much problems in real
 > > life. So I suggest we keep the spec as simple as possible and do not
 > > make exceptions in this case.
 > 
 > I agree with fantasai. The CSS statements @media not 3d-glasses { } or  
 > even @media not 3d-glasses,all { } are also dropped by media query aware  
 > user agents (such as Opera...).

Ok. If we consider it to be a question of dropping or not, rather than
one of binary logic, I guess we can quite easily specify this by
changing:

   Media queries involving unknown media types are always false.

to 

   Media queries involving unknown media types are always dropped.

I believe this will achieve the intended effects without causing other
problems.

Cheers,

-h&kon
              Håkon Wium Lie                          CTO °þe®ª
howcome@opera.com                  http://people.opera.com/howcome
Received on Wednesday, 9 January 2008 17:10:04 GMT

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