Re: [xml-dev] Concerned about the increasing reliance on XPath

[Stephen D Green <stephengreenubl@gmail.com>]

I think we tend to hope that XPath expressions can be
written such that they are immune from such implementation
specifics (like we would love to do with HTML) and we rush
into using it for standards and for writing XML Schema
schemas and Schematron schemas hoping that these too will
be implementation agnostic. Is that realistic? Is this the case
of our over-relying on it? Maybe in future XPath will become
what we need it to be but is it that yet?
----
Stephen D Green



On 9 May 2011 16:45, Stephen D Green <stephengreenubl@gmail.com> wrote:
> OK, but this adds to the description of my situation
> that developers have to know not just XPath and its
> expressions but the way XPath is implemented.
> ----
> Stephen D Green
>
>
>
> On 9 May 2011 16:38, Michael Kay <mike@saxonica.com> wrote:
>>
>>> Here is an example fragment
>>>
>>> <a xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; version-id="0.4"
>>>     xmlns="http://example.com";>
>>> ...
>>>
>>> In XPath 1.0
>>> /default:a/@version-id = 0.4 returns true
>>> but  /a/@version-id = 0.4 returns false
>>>
>>> In XPath 2.0
>>> /default:a/@version-id = 0.4 returns an error (prefix not bound)
>>> and  /a/@version-id = 0.4 returns true
>>>
>>> (I tried these out in Oxygen and I trust the results)
>>>
>>
>> These results are entirely attributable to the way in which oXygen defaults
>> the parameters controlling XPath evaluation (in particular the namespace
>> bindings), and not to the XPath specification itself. See:
>>
>> http://www.oxygenxml.com/forum/topic1538.html
>>
>> They could have chosen to make the bindings compatible between the two
>> versions, but they chose instead to take advantage of new features in the
>> language.
>>
>> You're right of course that namespaces are far and away the number one
>> usability problem in XPath for the majority of users, especially casual
>> users.
>>
>> Michael Kay
>> Saxonica
>>
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>