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Re: Single Node XPath Evaluation Is Ambiguous

From: Joseph Kesselman <keshlam@us.ibm.com>
Date: Wed, 6 Nov 2002 16:40:22 -0500
To: "WWW DOM" <www-dom@w3.org>
Message-ID: <OF28EC7066.3F5651E0-ON85256C69.00763EEF-85256C69.00772823@us.ibm.com>

If you aren't going to specify the order as explicitly called out by the 
XPath spec, I think it's wiser to not specify any order.

>If this does not happen, then an XPath processor that works differently 
to
>the rest, will mean the node returned from an unordered, single node
>evaluation will be ambiguous

It _IS_ inherently and deliberately ambiguous.  Unordered means no 
promises about order order, not a promise of interoperability with some 
ad-hoc most-common-this-week behavior.

If that isn't acceptable, don't use the "unordered single node" call; ask 
for the ordered set and take the appropriate member thereof, and hope that 
your implementation was clever enough to compute this incrementally and 
not waste time on the ones you don't care about.

>I am just asking that DOM XPath is aligned with XSLT for its
>unsorted, single node behaviour.

You're fairly explicitly asking for alignment with the current behavior of 
specific implementations. That's not an appropriate space for the DOM to 
be playing in, until and unless the XPath folks make that behavior part of 
their standard.

______________________________________
Joe Kesselman  / IBM Research
Received on Wednesday, 6 November 2002 16:40:57 GMT

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