RE: xsl:perform-sort (in 2.0)

> I just noticed this new instruction (although it was in the last draft
> as well)
> 
> Is there any difference bewteen
> 
>   <xsl:perform-sort select="$in">
>     <xsl:sort select="."/>
>   </xsl:perform-sort>
> 
> and
> 
>   <xsl:for-each select="$in">
>     <xsl:sort select="."/>
>     <xsl:copy-of select="."/>
>   </xsl:for-each>
> 
> either from a definitional or efficiency point of view?
> 

It's actually been there quite a while, and I think it's proving to be
perhaps the least-used new feature in the spec. It was put in as a
replacement for a sort() function which took a global sort specification as
an argument - rather like xsl:key and key() - but it doesn't seem to be
doing a very useful job.

Actually the equivalence is to:

   <xsl:for-each select="$in">
     <xsl:sort select="."/>
     <xsl:sequence select="."/>
   </xsl:for-each>

since no copying is involved.

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