[xsl] RE: Saxon versus Xalan implementations of evaluate() extension function?

["Michael Kay" <mike@xxxxxxxxxxxx>]

Saxon 8.x does too much optimization to be able to guarantee that variables
declared in the stylesheet actually exist as such at run-time (for example,
variables that are never referenced are ignored completely). So I decided to
disallow direct access to variables in saxon:evaluate(). Instead, you can
pass parameters $p1..p9 to the query, e.g.

saxon:evaluate("$p1 + 3", $x)

returns 5 if $x is initialized to 2.

Micahel Kay
http://www.saxonica.com/

> -----Original Message-----
> From: Andrzej Taramina [mailto:andrzej@xxxxxxxxxxx] 
> Sent: 07 July 2005 16:27
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Cc: mike@xxxxxxxxxxxx
> Subject: Re: Saxon versus Xalan implementations of evaluate() 
> extension function?
> 
> Adrian suggests:
> 
> > I think just doing all evaluations in a variable
> > beforehand should give you a bit more safety to work
> > in saxon/xalan/both. I was using xalan with the dyn
> > EXSLT extension and saxon and it seemed to work...
> > Although when I wanted to make it processor
> > independant to check beforehand what evaluate to use
> > like so... <xsl:apply-templates
> > use-when="function-available(dyn:evaluate)"
> > select="dyn:evaluate($evalThis)"/>, xalan 1.0
> > processor seemed to have a problem with the use-when
> > if this is an issue to work in both. I wasnt sure of a
> > workaround).
> 
> Is dyn:evaluate() availabe in Saxon 8.4? How about Saxon 6.5.4?
> 
> > but back to the problem, does this work?...
> > <xsl:variable name="evalThis" select="concat(
> > '$data/', @xpathValue )" />
> > ... saxon:evaluate( $evalThis )
> > 
> > at worst try this...
> > <xsl:variable name="evalThis" select="concat( $data,
> > '/', @xpathValue )" />
> > ... saxon:evaluate( $evalThis )
> 
> Won't work, since many times the variable $data is a node 
> set.  Xalan handles that fine.
> saxon:evaluate won't bind to the variable.
> 
> I tried reverting to Saxon 6.5.4 but then kept getting the 
> following exception:
> 
> javax.xml.transform.TransformerException: Error in expression 
> : Unexpected token EOF in
> expression
> 
> Anyone know what causes this exception and why Saxon 6.5.4 
> would throw this when Saxon 8.4
> and Xalan don't, on the same stylesheet source?
> 
> Thanks!
> 
> ....Andrzej
> 
> Chaeron Corporation
> http://www.chaeron.com