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Re: I18n comment: prefix binding mechanism

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Tue, 24 Jan 2006 10:14:57 +0100
To: "Felix Sasaki" <fsasaki@w3.org>
Cc: www-style@w3.org, public-i18n-core@w3.org
Message-ID: <dirbt19ogr5d5b87a73nr8j6p5m4r7k3r0@hive.bjoern.hoehrmann.de>

* Felix Sasaki wrote:
>> Selectors can be successfully implemented and used without any mechanism
>> to bind a namespace name to a prefix. Selectors that depend on a prefix
>> cannot be successfully processed in this case, and the draft defines how
>> implementations must handle this error. It is not possible through black
>> box testing whether implementations support namespaced selectors or not,
>> since the behavior is the same if there are no prefix bindings. Any
>> technology that uses Selectors in some way would need to define a prefix
>> binding mechanism to allow authors to use prefixes in selectors.
>>
>> It does not seem very useful to require any such technology to provide
>> this; the technology might be constrained e.g. to trees where elements
>> and attributes cannot be bound to a namespace, so any selector that uses
>> them would match nothing. The references as cited above are just
>> informative notes for people looking for more information. So no, there
>> is no dependency on the General Syntax module. Does this clarify the
>> situation?
>
>IMO the situation looks like:
>
>- CSS implementations of selectors: depend on syntax module & are fine.
>- other implementations of selectors: if they don't use namespaces, they  
>are fine, if not: nobody knows what should happen with namespace prefix  
>bindings.

Well, if there are no bindings available to the selectors engine, it
cannot sucessfully match any selector that depends on such bindings.
I'd agree that technologies that use css3-selectors and operate on
trees where elements and attributes can be bound to a namespace should
provide means to bind namespace prefixes, but I don't see the ambiguity.
Even in this case authors could still craft selectors that match based
on the local names of elements alone.

>Why is it not possible to formulate s.t. like "If selectors are used in a  
>language which incooperates the namespace mechanisms, the following  
>binding rules apply: ..."?

Selectors basically says whatever calls the selector engine must provide
a map from prefixes to namespace names; the engine then resolves such
prefixes in selectors using this map. When there is no binding, the
prefixes cannot be resolved and the selector that depends on them won't
be processed any further. If all required bindings are available, the
draft defines which elements match the selector. What rules are missing
in your opinion? I guess if you could fill in the "..." that would help
a lot.
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
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Received on Tuesday, 24 January 2006 09:20:53 GMT

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