Thanks for your help. I used the work around. I think the workaround is
more intuitive; but I had to declare the variables before the if condition,
since the scope of the variable seemed to be limited to the if block.
<xsl:variable name="StartTime"/>
<xsl:variable name="EndTime"/>
<xsl:if test="$TimeOption='SlidingTimes' or $TimeOption='SpecificTimes'">
<xsl:variable name="StartTime" select="substring-before($TimeValues,
';')"/>
</xsl:if>
<xsl:if test="$TimeOption='SlidingTimes' or $TimeOption='SpecificTimes'">
<xsl:variable name="EndTime" select="substring-after($TimeValues,
';')"/>
</xsl:if>
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05/06/2003 12:22 Subject: Re: test attribute
null evaluation doesn't work
PM
>This code evaluates to true when StartTime is not set.
> <xsl:when test="$StartTime">
>I want it to evaluate to false. It worked fine in xalan-1.
And the variable was set by....
<xsl:variable name="StartTime">
<xsl:if test="...">
<xsl:value-of select="substring-before($TimeValues, ';')"/>
</xsl:if>
</xsl:variable>
This probably represents a required tightening-up between 1.x and 2.x.
As you've structured it, $StartTime contains a result tree fragment
(RTF), which you should read about in a good XSLT book. The RTF is
never totally empty.
Fortunately, your case has the easy workaround of just inverting the
structure:
<xsl:if test="...">
<xsl:variable name="StartTime" select="..."/>
</xsl:if>
For more complicated situations, you could have a flag value that is
outside the range of valid times, or you could have a second boolean
variable $StartTimeSet to use in the xsl:when.
.................David Marston
