OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.


Help: OASIS Mailing Lists Help | MarkMail Help



   RE: [xml-dev] XML-aware programming language?

[ Lists Home | Date Index | Thread Index ]

> It seems odd to me that I've never seen an article comparing 
> actual XSLT and
> XQuery code for say moderately complex operations.

Apart from my Knight's Tour, which Jonathan cited (and which is a very
untypical application), I thought I'd try a very simple transformation that
I had to do recently. The task is to remove those parts of a document rooted
at an element having the attribute secret="yes". This is bog-standard XSLT
and doesn't need any 2.0 features:

<xsl:template match="*">
  <xsl:copy-of select="@*"/>

<xsl:template match="*[@secret='yes']"/>

7 lines, of which 6 are copy-and-paste from many other stylesheets that
you've written before. (Add two lines if you will for the header and

Here's an attempt at an XQuery solution:

declare function m:copy($e as element()) as element()? {
  if ($e/@secret = 'yes')
    then ()
    else element {node-name($e)} { 
           for $n in $e/node() return 
               if $n instance of element()
               then m:copy($n)
               else $n


14 lines of code (twice as much), and less scope for reuse. No great
difference in the conceptual difficulty - both require an understanding of
recursion - but I think XSLT emerges here as the winner. (And remember this
is only XSLT 1.0).

But in fact there's a bigger issue - the XQuery code is wrong. It loses the
namespaces from the source document. Perhaps I'm missing something, but I
can't see any way to solve this. XQuery may be computationally complete, but
it's not actually closed over the data model - there is no way of generating
a namespace dynamically. As far as I can see at the moment, that's a
stopper, and this exercise has to be coded in XSLT.

Of course, I'm sure there are other problems where XQuery has the edge.

Michael Kay


News | XML in Industry | Calendar | XML Registry
Marketplace | Resources | MyXML.org | Sponsors | Privacy Statement

Copyright 2001 XML.org. This site is hosted by OASIS