RE: sequence as function parameter

Thank you for your didactic explanations, Ken. It will help me next time I am
trying to complicate things :)

Regards,
Fabien


-----Message d'origine-----
De : G. Ken Holman [mailto:gkholman@xxxxxxxxxxxxxxxxxxxx]
Envoyi : lundi 4 juillet 2011 17:06
@ : xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Objet : Re:  sequence as function parameter

At 2011-07-04 16:46 +0200, Fabien Tillier wrote:
>I am trying to create a simple function to multiply each item in a
>sequence by each other (like a sum()).
>My problem is that I am unable to have the parameter treated as a node
>sequence (using saxon, so XSL2.0)
>
>I have
><xsl:template name=" multiplie">

That is a template, not a function, so I'm guessing we aren't looking
at the code that produced your result.  Perhaps you are simply
calling the template from the function?

>         <xsl:param name="serie"/>
>         <xsl:param name="result" as="xs:double"/>

Doesn't this have an initial value of 1?  Your template won't work if
you pass an initial sequence of only a single value because you are
multiplying that by the result and the result has no value.

>         <!--some test output -->
>         <xsl:value-of select="$serie"/>-<xsl:value-of
>select="$result"/>--
>         ###<xsl:value-of select="count($serie)"/>###
>         <!-- -->
>         <xsl:choose>
>                 <xsl:when test="count($serie) gt 1">
>                         <!-- make the multiplication between result and
>the first item in the serie, then remove it and call again -->
>                         <xsl:variable name="comp">
>                                 <xsl:value-of select="number($serie[1])
>* $result"/>
>                         </xsl:variable>

This is wastefully creating a node tree...

>                         <xsl:call-template name=" multiplie">
>                         <xsl:with-param name="serie"><xsl:copy-of
>select="subsequence($serie,2)"/></xsl:with-param>

... as is this ...

>                         <xsl:with-param name="result"><xsl:value-of
>select="$comp"/></xsl:with-param>

... and that.

>                         </xsl:call-template>
>                 </xsl:when>
>                 <xsl:otherwise>
>                         <xsl:value-of select="number($serie[1]) *
>$result"/>

Here is where your template won't work if you pass it an initial
sequence of a single value.

>...
>So, the part where I do a count gets me 1, when I should have 4...
>I have tried with
><xsl:param name="serie" as="node()*"/> but I have an error message
>XTTE0790: Required item type of first argument of multiplie() is node();
>supplied
>   value has item type xs:double

If you want to pass either nodes or atomic values then use:

   as="item()*"

>I am a bit out of ideas....

I think you are looking too deep.  And certainly your use of XSLT
constructs could be more streamlined.  I believe you can implement
your requirement completely in a one-line template with one parameter.

Does the example below help?

. . . . . . . . Ken

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:f="urn:X-Fabien"
   version="2.0">

<xsl:template match="/">
?<xsl:variable name="seq" select="(6.8E-06,5.5E-06,7.1E-06,7.3E-06)"/>
Fabien's test: <xsl:value-of select="f:multiplie($seq)"/>
Ken's tests: <xsl:value-of select="f:multiplie((7))"/>
and: <xsl:value-of select="f:multiplie((1,2,3,4,5))"/>
</xsl:template>

<xsl:function name="f:multiplie">
   <xsl:param name="seq" as="item()+"/><!--at least one item in sequence-->
   <xsl:sequence select="if( count($seq)=1 ) then $seq
                         else $seq[1] * f:multiplie($seq[position()>1])"/>
</xsl:function>
</xsl:stylesheet>

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