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Re: [selectors-api] SVG WG Review of Selectors API

From: Lachlan Hunt <lachlan.hunt@lachy.id.au>
Date: Wed, 28 Jan 2009 16:55:40 +0100
Message-ID: <49807FFC.5070306@lachy.id.au>
To: Giovanni Campagna <scampa.giovanni@gmail.com>
Cc: public-webapps@w3.org

Giovanni Campagna wrote:
> well, assuming that an author will need to match elements across
> multiple namespaces, it will be easier to use XPath (that also is
> compatible across multiple browsers) than to use horrible workarounds
> like "svg :not(foreignObject) *[href]" (all svg links) or "svg
> not(timesheet) animation" (all SVG but not SMIL animations), or
> "select[bind], select[ref]" (xforms selects)
> I think that those example are even easier to rewrite as
> "svg|*[href]", "svg|animation", "xforms|select", provided a reliable
> namespace binding mechanisms (the one I proposed)

The use case should try to answer the following questions.  Try to be as 
specific and realistic as possible, and provide links to real world 
examples if you can.

Let's go with the first example you gave of selecting all SVG links: 
"svg :not(foreignObject) *[href]".

Note that the example selector provided won't actually work to select 
all SVG links, at least not in the general case.  The only way that 
could work is like this:

"svg>:not(foreignObject)>[href],
  svg>:not(foreignObject)>:not(foreignObject)>[href],
  svg>:not(foreignObject)>:not(foreignObject)>:not(foreignObject)>[href],
  ..."


1. Why is the author mixing SVG and, presumably, HTML in this case?  I 
know there are use cases for this in general, but we should be specific 
about which.

2. Why does the SVG contain links?  This may be partially answered by 
the previous question.  Preumably this means that it's not meant as a 
purely decorative image and the links provide the user with something 
useful.

3. Why does the SVG image contain links using elements from a foreign 
namespace in addition to links using elements from its own namespace?

4. What is the author trying to achieve using a script that needs to 
obtain those links, and why does it only affect links from the SVG 
namespace, and not all links within the SVG image, including those from 
other namespaces within <foreignObject>?

If you can think of any other questions, feel free to ask them and 
answer them.  The more information we have about the use cases, the 
easier it will be to evaluate them and find an appropriate solution.

-- 
Lachlan Hunt - Opera Software
http://lachy.id.au/
http://www.opera.com/
Received on Wednesday, 28 January 2009 15:56:19 GMT

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