Re: XQuery Updates in XSLT

Robert Koberg wrote:

On Oct 29, 2008, at 3:48 PM, John Snelson wrote:

Robert Koberg wrote:

On Oct 29, 2008, at 3:21 PM, Scott Trenda wrote:

I think John is confusing the meaning of "functional" here. Dimitre
meant "functional" as in "based on functions/templates, like Haskell or
Scheme (as opposed to imperative)", and perhaps John interpreted
"functional" to mean "it works, it's not broken".

I am sure John knows what functional means. I was commenting about the
use of XQuery as opposed to xsl's identity template with some exception
templates. It sounds like he think XQuery is better at this type of
thing.

Yes. It's a few lines of easily readable XQuery Update, versus a few
complete XSLT templates and an explanation of how the identity transform
works.

Really? Show me how you use typeswitch (or whatever you would like to
use) to handle the XSL equivalent of exception templates in a few lines.

Problem: In a copy of the original document, rename the "name" attribute
of "product" elements to "id".

XQuery Update solution:

copy $a := doc(...)
modify for $p in $a//product return rename node $p/@name as "id"
return $a

XSLT 2.0 solution:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="2.0">

<xsl:template match="@*|node()">
 <xsl:copy>
   <xsl:apply-templates select="@*|node()"/>
 </xsl:copy>
</xsl:template>

<xsl:template match="product/@name">
 <xsl:attribute name="id">
   <xsl:value-of select="."/>
 </xsl:attribute>
</xsl:template>

</xsl:stylesheet>

The XQuery Update solution clearly matches the problem definition
better, and is shorter. It would be even shorter if you wanted to
perform the update in-place.

John

--
John Snelson, Oracle Corporation            http://snelson.org.uk/john
Berkeley DB XML:            http://oracle.com/database/berkeley-db/xml
XQilla:                                  http://xqilla.sourceforge.net