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Re: Quick Xpath

• To: Eric van der Vlist <vdv@d...>
• Subject: Re: Quick Xpath
• From: Uche Ogbuji <uche.ogbuji@f...>
• Date: Wed, 17 Jul 2002 20:23:35 -0600
• Cc: bob mcwhirter <bob@w...>, Mark Feblowitz <mfeblowitz@f...>, "'Jeni Tennison'" <jeni@j...>, Garland foster <garland_foster@s...>, "'Dare Obasanjo'" <dareo@m...>, xml-dev@l...
• In-reply-to: Message from Eric van der Vlist <vdv@d...> of "18 Jul 2002 00:49:48 +0200." <1026946189.19732.520.camel@ibook>
• Sender: uche.ogbuji@f...

> On Thu, 2002-07-18 at 00:39, bob mcwhirter wrote:
> > > Finally a word to say that even though the preceding-sibling is a
> > > "reverse" axis, a copy-of or apply-templates on "preceding-sibling::*"
> > > would take the nodes by document order: the "reverse order" property
> > > only affects the position -as returned by the "position()" function- of
> > > the nodes, not their physical position in the node set...
> > 
> > Though, unless otherwise specified (ie, in c14n), a node set is indeed
> > a -set-, with no particular order implied.
> 
> Reminds me of long threads, elsewhere,... we could argue that node sets
> are not -sets- in the sense that they have an order: if I affect
> "preceding-sibling::*" to a variable "var", then I can ask for $var[1]
> which would have no meaning if this was a -set- and the order used to
> evaluate $var[1] is the forward order even though the node set has been
> constructed using an axis with a reverse order.

Oh dear, Eric.  You're in for it now  :-)

I fought this battle a year or two ago on xsl-list and lost it to David 
Carlisle.  Node sets do not have order.  The specs do *impose* an ordering on 
them in certain areas, but this is not the same thing as their *having* order. 
 Because of this, and because generate-id() grants them an identity, they are 
indeed true sets.


-- 
Uche Ogbuji                                    Fourthought, Inc.
http://uche.ogbuji.net    http://4Suite.org    http://fourthought.com
Track chair, XML/Web Services One Boston: http://www.xmlconference.com/
The many heads of XML modeling - http://adtmag.com/article.asp?id=6393
Will XML live up to its promise? - http://www-106.ibm.com/developerworks/xml/li
brary/x-think11.html

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  • RE: Quick Xpath
    • From: Eric van der Vlist <vdv@d...>

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