Expressions in DISelect versus MQ

[Anne van Kesteren-2]

Hi,

It seems like the subset defined in  
http://www.w3.org/TR/2005/WD-cselection-20050502/#sec-expressions matches  
Media Queries http://www.w3.org/TR/2002/CR-css3-mediaqueries-20020708/ 
pretty closely except for the `di-cssmq-` prefix/namespace. What would the  
problem with having a (global) attribute that takes a media query like  
media="" in XHTML 2.0 (it currently only takes a CSS 2.0 medium I believe).

Cheers,

Anne


--
Anne van Kesteren
<http://annevankesteren.nl/>
<http://www.opera.com/>

[Max Froumentin]

Hi Anne,

"Anne van Kesteren" <annevk@...> writes:

> It seems like the subset defined in
> http://www.w3.org/TR/2005/WD-cselection-20050502/#sec-expressions
> matches  Media Queries
> http://www.w3.org/TR/2002/CR-css3-mediaqueries-20020708/  pretty
> closely except for the `di-cssmq-` prefix/namespace. What would the
> problem with having a (global) attribute that takes a media query like
> media="" in XHTML 2.0 (it currently only takes a CSS 2.0 medium I
> believe).

You've almost answered your own question: the media attribute in
XHTML2.0 _only_ takes a CSS2 media type (aural, braille, etc.).

That wasn't enough for the people who designed DIAL, and that's why the expr
attribute from DISelect allows complex XPath epxressions.

Now, if media accepted the same sort of expressions, there would be a
significant overlap which we'd have to sort out somehow, but at this time
the functionality offered by DISelect goes far beyond that of XHTML2's media.

Cheers,

Max.

[Bjoern Hoehrmann]

* Max Froumentin wrote:
>You've almost answered your own question: the media attribute in
>XHTML2.0 _only_ takes a CSS2 media type (aural, braille, etc.).

That sounds contrary to (member-only)

  http://lists.w3.org/Archives/Member/w3c-html-cg/2004JulSep/0007

Could you elaborate on why you think a hypothetical XHTML
2.0 Recommendation would have such a major design flaw?
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Weinh. Str. 22 · Telefon: [phone] · http://www.bjoernsworld.de
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[Max Froumentin]

Bjoern Hoehrmann <derhoermi@...> writes:

> * Max Froumentin wrote:
>>You've almost answered your own question: the media attribute in
>>XHTML2.0 _only_ takes a CSS2 media type (aural, braille, etc.).

> That sounds contrary to (member-only)

>   http://lists.w3.org/Archives/Member/w3c-html-cg/2004JulSep/0007

> Could you elaborate on why you think a hypothetical XHTML
> 2.0 Recommendation would have such a major design flaw?

I don't think I said there was a flaw anywhere. I'm just reading the
latest public XHTML2 specification.

Max.

[Anne van Kesteren-2]

On Wed, 17 May 2006 11:37:19 +0200, Max Froumentin <mf@...> wrote:
> You've almost answered your own question: the media attribute in
> XHTML2.0 _only_ takes a CSS2 media type (aural, braille, etc.).
>
> That wasn't enough for the people who designed DIAL, and that's why the  
> expr attribute from DISelect allows complex XPath epxressions.

Well, instead of inventing new things you could give comments (or ask) to  
the HTML WG regarding this. In the end I think, if XHTML 2.0 ever ends up  
being implemented, you would like to support media queries there. Just  
like media queries currently extends HTML4 in some way.

The DI WG could also introduce an attribute similar to media="" which does  
accept a media query.


--
Anne van Kesteren
<http://annevankesteren.nl/>
<http://www.opera.com/>

[Max Froumentin]

"Anne van Kesteren" <annevk@...> writes:

> On Wed, 17 May 2006 11:37:19 +0200, Max Froumentin <mf@...> wrote:
>> You've almost answered your own question: the media attribute in
>> XHTML2.0 _only_ takes a CSS2 media type (aural, braille, etc.).
>>
>> That wasn't enough for the people who designed DIAL, and that's why
>> the expr attribute from DISelect allows complex XPath epxressions.

> Well, instead of inventing new things you could give comments (or ask)
> to the HTML WG regarding this.

Discussions with the HTML WG, date back from 2003. See
<http://lists.w3.org/Archives/Member/w3c-html-cg/2003AprJun/0061.html>
for instance, (HCG, member only).

> In the end I think, if XHTML 2.0 ever ends up being implemented, you
> would like to support media queries there. Just like media queries
> currently extends HTML4 in some way.

I agree that this is an important topic, which has already been the subject of
discussions between the CSS and DI groups (see
<http://lists.w3.org/Archives/Member/w3c-css-wg/2006JanMar/0250.html>).

> The DI WG could also introduce an attribute similar to media="" which
> does accept a media query.

Yes, or they could just import media in DIAL. I don't how sel:expr and
media would interact when used together but it may make sense to allow
both (in different places).

The problem is the simplicity of media queries versus the power of
XPath, of course.  And also the speed of deployment: at the moment,
XHTML2 doesn't have the power that device independent content authors
require. And they want something quickly.

Max.

[Anne van Kesteren-2]

On Wed, 17 May 2006 15:18:13 +0200, Max Froumentin <mf@...> wrote:

>>> You've almost answered your own question: the media attribute in
>>> XHTML2.0 _only_ takes a CSS2 media type (aural, braille, etc.).
>>>
>>> That wasn't enough for the people who designed DIAL, and that's why
>>> the expr attribute from DISelect allows complex XPath epxressions.
>>
>> Well, instead of inventing new things you could give comments (or ask)
>> to the HTML WG regarding this.
>
> Discussions with the HTML WG, date back from 2003. See
> <http://lists.w3.org/Archives/Member/w3c-html-cg/2003AprJun/0061.html>
> for instance, (HCG, member only).

So what's the problem?

>> In the end I think, if XHTML 2.0 ever ends up being implemented, you
>> would like to support media queries there. Just like media queries
>> currently extends HTML4 in some way.
>
> I agree that this is an important topic, which has already been the  
> subject of
> discussions between the CSS and DI groups (see
> <http://lists.w3.org/Archives/Member/w3c-css-wg/2006JanMar/0250.html>).
>
>> The DI WG could also introduce an attribute similar to media="" which
>> does accept a media query.
>
> Yes, or they could just import media in DIAL. I don't how sel:expr and
> media would interact when used together but it may make sense to allow
> both (in different places).

Yeah, make it even more complicated :-) media="" and sel:expr do quite  
different things as I understand it though. It seems that media="" only  
changes that what's rendered and sel:expr actually changes the resulting  
document (as it's supposedly preprocessed or something like that).


> The problem is the simplicity of media queries versus the power of
> XPath, of course.  And also the speed of deployment: at the moment,
> XHTML2 doesn't have the power that device independent content authors
> require. And they want something quickly.

I don't see how XPath is more powerful here, actually. Especially when  
used as the DI WG uses it within sel:expr. Could you give some specific  
examples?

Also, with regard to what device independent content authors want, I'm not  
really sure if more functionality is one of their requirements... Being  
able to deploy some HTML page and have it just work (perhaps with a  
special handheld style sheet if the author thought of that and had the  
time to do QA on it) seems far better to me than having to learn  
namespaces, XPath and a whole let of other things DIAL and DISelect seem  
to import.


--
Anne van Kesteren
<http://annevankesteren.nl/>
<http://www.opera.com/>