[xsl] Re: Re: A question about the expressive power and limitations of XPath 2.0

[Dimitre Novatchev <dnovatchev at yahoo dot com>]

> > As I'm just starting to read the latest WDs, I'd greatly appreciate
> > it if somebody could provide examples showing:
> >
> > 1. A problem, which cannot be easily solved by using "for", but
> > which has a natural recursive solution. Calling user-defined
> > functions within an XPath expression must be excluded, as we can do
> > anything (e.g. recursion) within a user-defined function.
> 
> Perhaps the implementation of a math:power function? You can do that
> with recursion using:
> 
> <xsl:function name="math:power">
>   <xsl:param name="base" type="xs:float" select="1" />
>   <xsl:param name="power" type="xs:integer" select="0" />
>   <xsl:result select="if ($power = 0)
>                       then 1
>                       else $base * math:power($base, $power - 1)" />
> </xsl:function>

Hi Jeni,

A general statement about what "for" cannot do: Any problem of sequence processing,
which requires that the result of processing an item be used as input for processing
the next item(s).

Is this true?

Then an example with sales and having to compute the total sum, but also having to
maintain a ***running total*** seems most close to earth.

Do you see anything wrong in my reasoning?

Cheers,
Dimitre.




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