[saxon] casting result tree fragment to boolean

[David Allouche <david@xxxxxxxxxxxxxxxx>]

Hello,

this is another post of the same kind as the previous one, just to make
sure I am not misunderstanding XSLT:
 
 - something works a way I don't expect it to
 - is it an abnormal behavior of saxon ?
 - if yes, there is a workaround

Here is the crash course:

- - - xsl-1.xsl - - - 
<?xml version="1.0"?> 
<xsl:stylesheet version="1.0"
		xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>

  <xsl:template match="/">
    <xsl:variable name="flag">
      <xsl:call-template name="empty"/>
    </xsl:variable>
    <xsl:if test="$flag">
      <xsl:message>No result means true ???</xsl:message>
    </xsl:if>
    <xsl:if test="boolean($flag)">
      <xsl:message>Even with explicit boolean cast !</xsl:message>
    </xsl:if>
    <xsl:if test="not(string($flag))">
      <xsl:message>But no result converted to string means
false...</xsl:message>
    </xsl:if>
    <xsl:variable name="other-flag">
      <xsl:call-template name="empty"/>
    </xsl:variable>
  </xsl:template>

  <xsl:template name="empty"/>
  
</xsl:stylesheet>
- - - - - - - - - - -

- - - dummy.xml - - - 
<?xml version="1.0" encoding="iso-8859-1"?> 

<dummy/>
- - - - - - - - - - -

- - - shell log - - -
$ java com.icl.saxon.StyleSheet dummy.xml xsl-1.xsl
No result means true ???
Even with explicit boolean cast !
But no result converted to string means false...
<?xml version="1.0" encoding="utf-8"?>
- - - - - - - - - - - 

Here is what is said in "XSLT Programmer's Reference" about converting a
result tree fragment to a boolean (p. 427)

- - - XSLT Programmer's Reference - - -
The result tree fragment is first converted to a string, and the string is
then converted to a Boolean.  The resulting boolean is true if the result
tree fragment contains any non-empty text nodes, and is false otherwise.
- - - - - - - - - - - - - - - - - - - - 

Once again, either I am deeply misunderstanding something, or the book and
the program are not coherent...


                             -- David --


PS: Is Mike Kay still reading the list ?


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