Article:		Comparing XSLT and XQuery
Subject:		Off Target
Date:		2005-03-11 16:13:14
From:		J David Eisenberg
Response to: Off Target
I should get an award for "worst. simile. ever." Let me put it this way: XSLT (any version) does have an underlying type system, but your XSLT stylesheet doesn't have to specify the datatype of everything; you can even skip the as="" attribute on xsl:param if you so desire. XSLT tends to handle string/number/node-to-text conversions without a lot of fuss--it almost always delivers a reasonable result, even if it's not what you'd ideally like. XQuery tends to be more vocal if you don't specify types. I'm not saying that one way is "better" or "worse" - that depends on your philosophy and the task at hand. But yeah, that simile was really awful.

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• Off Target
  2005-03-11 20:35:09 dnovatchev
  
  > Let me put it this way:

  
  > XSLT (any version) does have an underlying
  > type system, but your XSLT stylesheet doesn't
  > have to specify the datatype of everything;
  > you can even skip the as="" attribute on
  > xsl:param if you so desire. XSLT tends to
  > handle string/number/node-to-text conversions
  > without a lot of fuss--it almost always
  > delivers a reasonable result, even if it's not
  > what you'd ideally like.

  
  Quite *not* so. I don't think anyone who has actually written XSLT 2.0 code will make the quoted statement.

  
  XSLT 2.0 uses XPath 2.0 which has stringent type-checking rules.

  
  For example, even something as simple as the following transformation raises type errors, as evidenced using Saxon 8.3B:

  
  <xsl:stylesheet version="2.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  >
  
  <xsl:template match="/">
  <xsl:copy-of select="*/*
  [3 < substring(@n,2)]"/>
  </xsl:template>
  </xsl:stylesheet>

  
  when applied on this source xml document:

  
  <t>
  <x n="n1"/>
  <x n="n2"/>
  <x n="n3"/>
  <x n="n4"/>
  <x n="n5"/>
  </t>

  
  the result is:

  
  Saxon 8.3 from Saxonica
  Java version 1.5.0_01
  Error at xsl:copy-of on line 6 of file:/C:/Program%20Files/Java/jdk1.5.0_01/bin/marrowtr.xsl:
  XP0006: Cannot compare xs:integer to xs:string
  Failed to compile stylesheet. 1 error detected.

  
  
  Best regards,
  Dimitre Novatchev.
  
  

  • Off Target
    2005-03-11 21:58:12 J David Eisenberg
    
    A quick further note: I also have been testing some XSLT files I wrote for transforming XML to OpenOffice.org files; I just changed the version to 2.0 and everything continued to work. I guess I was unlucky enough to write transformations that didn't hit any of the type problems.
    
    
    • Off Target
      2005-03-11 22:23:59 dnovatchev
      
      Yes, this may happen and is indeed a question of luck.

      
      Specifying version="1.0" causes the XSLT processor to work in "backwards compatibility mode" but even in this case the XSLT processor uses the XPath 2.0 data model -- therefore it does not completely behave as an XSLT 1.0 processor.

      
      Best regards,
      Dimitre Novatchev
      
      

  • Off Target
    2005-03-11 21:15:58 J David Eisenberg
    
    You're right; my experience with 2.0 is fairly limited, and that's what I get for running a test transformation in Saxon without changing the version from 1.0 to 2.0.
    
    
  • Off Target
    2005-03-11 20:40:13 dnovatchev
    
    I wrote:

    
    <xsl:copy-of select="*/*
    [3 < substring(@n,2)]"/>
    </xsl:template>

    
    Of course, the "less-than" operator was written escaped, however it is displayed as"<" -- I just don't know how to enter xslt code so that it would be properly displayed on this site -- anyway, the example is very simple and must be clear.

    
    Dimitre Novatchev