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Re: [selectors-api] Proposal to Drop NSResolver from Selectors API v1

From: Maciej Stachowiak <mjs@apple.com>
Date: Mon, 12 May 2008 07:13:08 -0700
Cc: public-webapi <public-webapi@w3.org>
Message-Id: <B93FF47B-17CD-46C0-961A-5ED14EC668EB@apple.com>
To: Bjoern Hoehrmann <derhoermi@gmx.net>


On May 12, 2008, at 5:52 AM, Bjoern Hoehrmann wrote:

> * Maciej Stachowiak wrote:
>> A function is not a particularly convenient way to specify a  
>> namespace
>> mapping, and it creates these error handling issues as well as  
>> causing
>> problems with case (in)sensitivity. Even though NSResolver is what
>> XPath uses, wouldn't it be simpler to just accept an object that
>> provides the relevant namespace mappings?
>
> That would preclude simple solutions to the resolution problem like
> http://lists.w3.org/Archives/Public/public-webapi/2008Apr/0204.html
>
>> I originally thought that >this could be a JSON-style JavaScript  
>> object,
>> but it seems to me that a DOM node would actually work just as well.
>> Most of the time, you want to use the namespace prefixes in effect  
>> for
>> the root element, and if not, then it is pretty simple to construct a
>> DOM node with all the right xmlns declarations.
>
> That would not have the particular problem above, but many others.
> I do not think you want the prefixes on the document element most
> of the time, it is not as easy to create such a node as you suggest,
> and all in all this would likely cause great confusion. It's hard
> to imagine the typical user of this API using code like this:
>
>  var node = document.createElementNS(null, "magic-ns-element");
>  node.setAttributeNS('http://www.w3.org/2000/xmlns/',
>    'xmlns:xht', 'http://www.w3.org/1999/xhtml');
>  node.setAttributeNS('http://www.w3.org/2000/xmlns/',
>    'xmlns:svg', 'http://www.w3.org/2000/svg');
>  node.setAttributeNS('http://www.w3.org/2000/xmlns/',
>    'xmlns:mml', 'http://www.w3.org/1998/Math/MathML');
>
> I think this would be a very bad idea.

This does not look much better (it does avoid repeatedly mentioning  
the xmlns namespace at least):

function resolver(prefix) {
     if (prefix == "xht") {
	return "http://www.w3.org/1999/xhtml";
     } else if if (prefix == "svg") {
	return "http://www.w3.org/2000/svg";
     } else if (prefix == "mml") {
	return "http://www.w3.org/2000/xmlns/";
     }
     return null; // ???
}

However, this does look better:

var namespaces = {xht: "http://www.w3.org/1999/xhtml"; svg: "http://www.w3.org/2000/svg 
"; mml: "http://www.w3.org/1998/Math/MathML" };

I therefore make a second proposal to accept either vanilla JS objects  
of this format or DOM nodes, instead of NSResolver objects.

Regards,
Maciej
Received on Monday, 12 May 2008 14:13:54 GMT

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