XSLT variables and parameters don't have a value until run-time, so you
can't refer to them in use-when. What you can do instead is to refer to Java
system properties

use-when="system-property('slenderise.level') = '1'"

which you can set from the command line using -Dslenderise.level=1 or from a
calling Java application using System.setProperty().

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

> -----Original Message-----
> From: Georges Schmitz [mailto:georges.schmitz@xxxxxxxxx] 
> Sent: 02 March 2007 10:30
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [xsl] dynamically set priority in xsl:template
> 
> Andrew Welch wrote:
> > On 3/2/07, Georges Schmitz <georges.schmitz@xxxxxxxxx> wrote:
> >> I want to dynamically set the priority of a template (with 
> >> $expand.level), with the objective to control the "amount 
> of output"
> >> from outside the stylesheet via parameter setting.
> >>
> >>   <xsl:param name="slenderise.level" select="-1" />
> >>
> >>   <xsl:template match="@db:type |
> >>                        @db:size |
> >>                        @db:nullable"
> >>                        mode="slenderise"
> >>                        priority="$slenderise.level" />
> >
> ...
> > <xsl:variable name="suppress" select="tokenize($names, ' ')"
> > as="xs:string*"/>
> Thank you for this hint, but it isn't practicable for me (I 
> gave just a simplified example); the stylesheet is rather 
> complex: 11 apply-templates in mode "slenderise" ...
> 
> I would prefer the "pass-fail" solution proposed by Michael 
> Kay, but when I tried the following, I get again an error:
>   <xsl:template match="@db:type |
>                        @db:size |
>                        @db:nullable"
>                        mode="slenderise"
>                        priority="2" />
>                        use-when="$slenderise.level = 1"
> 
> ==>
>    XPST0008: Error in use-when expression. XPath syntax error 
> at char 18 on line 211 in
>   {$slenderise.level = 1}:
>     Variable $slenderise.level has not been declared
> 
> The parameter is definitively set, so what is wrong? 
> "$slenderise.level = 1" can be evaluated to a boolean, or am 
> I missing another thing?