Put the conditional inside the expression that initializes the variable:

<xsl:variable name="x">
  <xsl:value-of select="$url"/>
  <xsl:if test="child::area">?<xsl:value-of select="child::area"/></xsl:if>
  <xsl:if test="child::action">&amp;<xsl:value-of
select="child::action"/></xsl:if>
</xsl:variable>

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

> -----Original Message-----
> From: Adam J Knight [mailto:adam@xxxxxxxxxxxxxxxxx] 
> Sent: 07 May 2005 09:06
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  Building Dynamic Urls
> 
> Hi all,
> 
>   I am wanting to build dynamic urls in xslt by using string 
> concatenation,
> unless there is a better way. My stylesheet will be sent a 
> $url parameter to
> provide the base of the url. From their my logic is as follows:
>     
> <xsl:if test="child::area">
>   Building_url = $url and "?area=" and <xsl:value-of select="area"/>
> </xsl:if>
> 
> <xsl:if test="child::action">
>   Building_url = $url and "&action=" and <xsl:value-of 
> select="action"/>
> </xsl:if>
> 
> <xsl:if test="child::page">
>   Building_url = $url and "&page=" and <xsl:value-of select="page"/>
> </xsl:if>
> 
> I as I understand it, xsl variables can't be changed once 
> given a value.
> So what would be the best way to go about building these dynamic urls.
> 
> Help appreciated!
> 
> Cheers, 
> Adam