This shouldn't be a dark corner, because the fact that nodes have identity
is pretty fundamental, but sadly there are lots of people who aren't aware
of the implications. The answer of course is (2).

Michael Kay
http://www.saxonica.com/  

> -----Original Message-----
> From: Oleg A. Paraschenko [mailto:olpa@x...] 
> Sent: 01 September 2005 20:45
> To: xml-dev
> Subject: [xml-dev] quiz on select vs copy-of
> 
>   Hello,
> 
>   do you know the dark corners of XSLT? Here is one. Compare two
> variables:
> 
> <xsl:variable name="v1" select="some-xpath"/>
> <xsl:variable name="v2"><xsl:copy-of 
> select="some-xpath"/></xsl:variable>
> 
>   Are "v1" and "v2" the same? I mean: can "v1" and "v2" be used in a
> program interchangeably? Answers:
> 
> 1) yes
> 2) no
> 3) implementation-dependant
> 
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
> .
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> .
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> 
>   The right answer is (2): no. Changing a use of "v1" to 
> "v2", or reverse,
> might change the result of a stylesheet. I'll post an example 
> later. Or
> you can provide your version.
> 
> 
> -- 
> Oleg Paraschenko  olpa@ http://xmlhack.ru/  XML news in Russian
> http://uucode.com/blog/  Generative Programming, XML, TeX, Scheme
> 
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