Re: xslt 2, forward compatibility mode.

Michael Kay wrote:
> Suppose that XSLT 3.0 has just been published, and it includes a new
> <xsl:perform-magic> instruction, which is implemented in Saxon version
> 19.2, but not yet in MSXML6. You want to invoke this instruction when
> your stylesheet is running under Saxon, but when running under MSXML6,
> you just want to leave out that part of the output. So you write:
> 
> <xsl:template match="thing" version="3.0">
>   <xsl:perform-magic select="magic-dust">
>     <xsl:fallback>Sorry, Microsoft don't do magic</xsl:fallback>
>   </xsl:perform-magic>
> </xsl:template>
> 
> Specifying version="3.0" means that the Microsoft processor (or any XSLT
> 1.0 or 2.0 processor) is obliged to execute the xsl:fallback
> instruction. If you had said version="1.0" or version="2.0", then the
> processor would instead have thrown a static error saying that there is
> no such instruction as xsl:perform-magic.

That does not work.

% cat fallback.xsl
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:output method="xml" indent="yes"/>

  <xsl:template match="/" version="3.0">
    <result>
      <xsl:perform-magic select="magic-dust">
        <xsl:fallback>Sorry, we don't do magic</xsl:fallback>
      </xsl:perform-magic>
    </result>
  </xsl:template>

</xsl:stylesheet>

% saxon dummy.xml fallback.xsl
Error at xsl:template on line 7 of file:/opus/home/mike/xml/test/fallback.xsl:
  Attribute version is not allowed on this element
Error at xsl:perform-magic on line 9 of file:/opus/home/mike/xml/test/fallback.xsl:
  Unknown XSLT element: perform-magic
Transformation failed: Failed to compile stylesheet. 2 errors detected.

Mike

-- 
  Mike J. Brown   |  http://skew.org/~mike/resume/
  Denver, CO, USA |  http://skew.org/xml/

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