[xsl] Recursive sums in xslt 1.0

[Daniel O'Donnell <daniel.odonnell@xxxxxxxx>]

Hi,
I'm returning to a problem I asked a couple of weeks ago about node 
tests 
<http://www.biglist.com/lists/xsl-list/archives/200503/msg00088.html>. 
I've been working through the XSL 2.0 and XSL 1.0 suggestions proposed 
at the time by David Carlisle 
<http://www.biglist.com/lists/xsl-list/archives/200503/msg00089.html> 
and Wendell Piez 
<http://www.biglist.com/lists/xsl-list/archives/200503/msg00159.html>. 
I've listed the problem at the end of this e-mail.

The xslt 1.0 solution proposed was:

> in xslt1 if you want to store an expression that is going to be
> re-evaluated you need to put it in a named template. Then you could call
> that so long as you replaced sum(..) with a recursive template that
> iterated over the nodes calculating the sum and calling your named
> templates.

I understand the named template, of course. I don't understand the 
second sentence, though. How would this work? I'm raising the question 
here rather than privately, because it seems like an important technique 
that might be useful (and difficult) for others like myself you are 
(now) probably more than beginners but less than experts.


The problem from my original e-mail:
> The context is a financial xslt file that outputs itemised monthly
> reports from an unitemised year-to-date xml file.  For each item in the
> output file, I need to do two tests: one for date and the other for some
> other feature (usually party [i.e. payer/payee]). This would be an
> example with no parameters or variables:
>
>
> <xsl:variable name="actualelectricity">
> <xsl:value-of select="sum(/statement/item[date >= 20050228 and party[contains('DEML')]]/amount)"/>
> </xsl:variable>
>
>
> What I want to do is turn the two expressions in the test into
> independent variables so that I could do something like this:
>
>
> <xsl:variable name="actualelectricity"> <xsl:value-of select="sum(/statement/item[$datetest and $electricitytest]/amount)"/>
> </xsl:variable>
>
> Where
>
> datetest = (date >= 20050228)
>
> and
>
> electricitytest = (party[contains('DEML')])
>
> The reason for doing this is that it allows me to reuse the category tests (i.e. the party[contains()]-type tests) independently of the date tests: for year-to-date summaries, and for a miscellaneous class that consists of anything that is not identified by an explicit category test.


--
Daniel Paul O'Donnell, PhD
Associate Professor of English
University of Lethbridge
Lethbridge AB T1K 3M4
Tel. (403) 329-2377
Fax. (403) 382-7191
E-mail <daniel.odonnell@xxxxxxxx>
Home Page <http://people.uleth.ca/~daniel.odonnell/>
The Digital Medievalist Project: <http://www.digitalmedievalist.org/>