XSL Transformations Requirements Version 1.1 - a crazy idea?

[Francis Norton <francis@xxxxxxxxxxx>]

The Requirements Document contains a reuirement for Portable Extension
Functions Implementations
(
http://www.w3.org/TR/2000/WD-xslt11req-20000825#section-Requirements-for-Portable-Extension-Function-Implementations
).

This discusses ways to make sure that extensions in Java or EcmaScript
will be portable between XSLT implementations, while specifically making
support for extensions in *any* language an optional feature.

The "Crazy Idea" thread from September 1999 came up with some
interesting ideas for allowing extension functions in XSLT itself - for
example, James Clark's reply:

<quote
src="http://www.mulberrytech.com/xsl/xsl-list/archive/msg05080.html";>

> I was thinking of an extension to XSLT (I know, it's too late for this
> version).
> 
> Something like:
> 
> <xsl:function name="reverse" namespace:fn="www.redrice.com">
>         <xsl:param name="string" />
>         <xsl:if test="$string">
>                 <xsl:value-of select="fn:reverse(substring($string,2))" />
>         </xsl:if>
>         <xsl:value-of select="substring($string,1,1)" />
> </xsl:function>
> 
> so I could then call it with
> 
> <xsl:stylesheet indent-result="yes" default-space="strip"
>         xmlns:xsl="http://www.w3.org/XSL/Transform/1.0";
>         xmlns:fn="www.redrice.com">
> 
> ...
> 
> <xsl:value-of select="fn:reverse('able was I ere I saw Elba')" />

The trouble with that is that functions would only be able to return
result tree fragments. I had been thinking of something like:

<xsl:variable name="reverse"
 select="function($s)
          (concat($s ? $reverse(substring($s,2)) : '',
substring($s,1,1)))"/>

<xsl:value-of select="$reverse('able was I ere I saw Elba')"/>

Something like you suggest would be useful too (I would think of it as a
way to call named templates from functions).

There are plenty of interesting possibilities for XSLT/XPath v2.

James

</quote>

If such a proposal was easy to implement, and could be shown to be
"syntax sugar" - then would it not be a good idea to specify and indeed
mandate it for XSLT 1.1 as the ultimate in portable extension function
support?

Francis.
-- 
Francis Norton.

Defy Convention? Deify Convention!


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