The reason it doesn't work in Xalan is that xsl:function is an XSLT 2.0
construct, and Xalan doesn't support XSLT 2.0.

It's probably marginally faster to use Saxon's native dateTime support, but
I doubt it makes a very big difference:

<xsl:function name="my:compDate" as="xs:boolean">
  <xsl:param name="dt_a" as="xs:string" />
  <xsl:param name="dt_b" as="xs:string" />
  <xsl:sequence select="xs:dateTime(dt_a) gt xs:dateTime(dt_b)"/>
</xsl:function>

This isn't 100% identical, for example Saxon will throw a wobbly if the date
is 2005-02-29.

Note that you could use the <xsl:sequence select="(boolean expression)"/> in
your version as well.

Also, you could get rid of all three punctuation characters in a single call
on translate.

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

> -----Original Message-----
> From: Jeffrey Schrab [mailto:jschrab@xxxxxxxxxxxx] 
> Sent: 21 September 2005 20:53
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  XSLT function optimization - datetime comparisons?
> 
> I don't profess to be well seasoned in XSLT.  Simply put I 
> have a function that I call an awful lot in stylesheet.  I'm 
> wondering if I'm being very inefficient about how it's coded. 
>  Does anyone have any comments how best to do the comparison 
> that I'm doing below for datetimes of the form YYYY-MM-DDTHH:MM:SS ?
> 
> I'm using Saxon - I found that Xalan (2.7) just couldn't do 
> this sort of thing for reasons I don't understand to this day.
> 
> 
> <xsl:function name="my:compDate" as="xs:boolean">
> 	<xsl:param name="dt_a" as="xs:string" />
> 	<xsl:param name="dt_b" as="xs:string" />
> 	<xsl:choose>
> 		<xsl:when test="
> xs:integer(translate(translate(translate($dt_a,'-',''),'T','')
> ,':','')) gt 
> xs:integer(translate(translate(translate($dt_b,'-',''),'T','')
> ,':',''))">
> 			<xsl:copy-of select="true()"/>
> 		</xsl:when>
> 		<xsl:otherwise>
> 			<xsl:copy-of select="false()"/>
> 		</xsl:otherwise>
> 	</xsl:choose>
> </xsl:function>
> 
> -- 
> Jeffrey Schrab
> Internet Application Developer
> 
> GS Design
> 6665 N. Sidney Place
> Milwaukee, WI 53209
> 
> P: 414.228.9666
> F: 414.228.9652
> E: jschrab@xxxxxxxxxxxx http://www.gsdesign.com