Re: [xsl] Dynamic XPath expression (I know it doesnt work in XSLT1.0)

[Matt Dittbenner <mbditt@xxxxxxxxxxxxxxxxx>]

Thanks a lot!
We were not aware of that syntax and that solved the issue.

One correction. The code that we needed is a little different than what 
you have below. It should be:
----
<xsl:copy-of select="saxon:evaluate(concat('$p1', $path), $contentDoc)"/>
----

Thanks!
Matt

Michael Kay wrote:

> One of the challenges in defining an evaluate() function is determining what
> the evaluation context should be. In Saxon, variables that are not
> referenced anywhere in the stylesheet disappear completely at compile time
> (I've seen stylesheets that import a module that defines 100 global
> variables of which only three are used). I didn't want to keep extra
> overhead around at run-time just in case someone decides to use
> saxon:evaluate to access it, so I decided that stylesheet variables would
> not be part of the context for the dynamic expression.
>
> Instead you can pass explicit parameters: 
>
> <xsl:copy-of 
>  select="saxon:evaluate(concat('$contentDoc', $p1), $path)"/>
>
> This binds $p1 within the expression to the second argument of
> saxon:evaluate, whose value is the value of $path.
>
> Full details at
> http://www.saxonica.com/documentation/extensions/functions/evaluate.html
>
> Michael Kay 
>
>  
>
> > -----Original Message-----
> > From: Matt Dittbenner [mailto:mbditt@xxxxxxxxxxxxxxxxx] 
> > Sent: 26 August 2004 20:12
> > To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> > Subject: Re: [xsl] Dynamic XPath expression (I know it doesnt 
> > work in XSLT1.0)
> >
> > We have tested the evaluate function in saxon and it seems to 
> > run with 
> > no detectable slow down.
> >
> > We are having an issue using a global variable in the string. Here is 
> > the code:
> > -------
> >        <xsl:variable name="path" select="@path"/>
> >        <xsl:copy-of 
> > select="saxon:evaluate(concat('$contentDoc', $path))"/>
> > ---------
> >
> > This is what saxon returns:
> > ---------
> > Warning: org.xml.sax.SAXParseException: Using original entity 
> > definition 
> > for "&quot;".
> > Warning: org.xml.sax.SAXParseException: Using original entity 
> > definition 
> > for "&amp;".
> > Warning: org.xml.sax.SAXParseException: Using original entity 
> > definition 
> > for "&lt;".
> > Warning: org.xml.sax.SAXParseException: Using original entity 
> > definition 
> > for "&gt;".
> > Warning: org.xml.sax.SAXParseException: Using original entity 
> > definition 
> > for "&apos;".
> > Error at copy-of on line 107 of 
> > file:/var/www/localhost/site_system/master/data/cihost.com/tra
> > nsformation/layout.xsl:
> >  Variable $contentDoc has not been declared
> > Transformation failed: Run-time errors were reported
> > -------
> >
> > It seems that the variable $contentDoc is not accessible from 
> > wherever 
> > it's being evaluated.
> >
> > Here is where we declare the variable:
> > --------
> > <?xml version="1.0" ?>
> > <xsl:stylesheet version="1.0"
> >        xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
> >        xmlns:xhtml="http://www.w3.org/1999/xhtml";
> >        xmlns:pd="http://www.plauditdesign.com/pd";
> >        xmlns:saxon="http://saxon.sf.net/";
> >        xmlns="http://www.w3.org/1999/xhtml";>
> >   
> >    <xsl:output
> >        method="xml"
> >        version="1.0"
> >        encoding="iso-8859-1"
> >        indent="no"
> >        omit-xml-declaration="no"/>
> >
> >    <!-- Incoming Content -->
> >    <xsl:param name="content"/>
> >    <xsl:variable name="contentDoc" select="document($content)"/>
> > -------
> >
> > Last thing I should probably note is that we are using Saxon 7.8
> >
> > Thanks,
> > Matt
> >
> >
> > Michael Kay wrote:
> >
> >    
> >
> > > > After some pretty exhaustive searching on the web, I have 
> > > >        
> > decided to 
> >    
> >
> > > > join the list. I have noticed in the archives that more than 
> > > > one person 
> > > > has had the same issue as I have...how to create an XPath 
> > > >        
> > expression 
> >    
> >
> > > > dynamically (from a variable, etc). The answer to these 
> > > > questions was to 
> > > > use any of the available *:evaluate functions. I would like 
> > > >        
> > to try to 
> >    
> >
> > > > avoid that, since it increases the parse time so much....and 
> > > > that is not 
> > > > acceptable.
> > > >
> > > > My question is if there is any other way to accomplish this, 
> > > > for example using XSLT2.0. 
> > > >   
> > > >
> > > >        
> > > Sorry, but this is one feature that we decided not to put in 
> > >      
> > XSLT 2.0. The
> >    
> >
> > > only choices are really:
> > >
> > > (a) using an xx:evaluate() extension function
> > > (b) modifying the stylesheet before you execute it
> > >
> > > I'm not sure why you think there is a performance problem 
> > >      
> > with the extension
> >    
> >
> > > function approach?
> > >
> > > Michael Kay