Re: [xsl] [exsl] Draft 0.1 - call for comments

[Uche Ogbuji <uche dot ogbuji at fourthought dot com>]

> As a further extension to exsl:function, I think it would be useful to be
> able to specify that the XSLT function should only be used if an appropriate
> built-in function is not available. In some cases, you might want to do the
> reverse, and override a built-in extension function.
> 
>   e.g.
>       <exsl:function name="set:intersection" prefer="saxon:intersection">
>       <exsl:function name="set:intersection" prefer="saxon:intersection
>         xt:intersection my-processor:intersection">
>       <exsl:function name="set:intersection" override="saxon:intersection">
> 
> In the first example, any calls to set:intersection would call the built-in
> saxon:intersection. In the last example, calls to saxon:intersection would
> call the XSLT function instead.

Not a bad idea in general as a compatibility bridge, but is it practical?  
Aren'tmany of the exsl extensions likely to have some differences from the 
vendor-specific ones?


> The real benefit would be that the namespace prefix could be omitted from
> the prefer or override attribute values to affect any extension function of
> that name on a particular implementation.
> 
>       <exsl:function name="set:intersection" prefer="intersection">
>       <exsl:function name="set:intersection" override="intersection">
> or, perhaps:
>       <exsl:function name="set:intersection" prefer="*:intersection">
>       <exsl:function name="set:intersection" override="*:intersection">
> or, even better?
>       <exsl:function name="set:intersection" prefer-builtin="true()">
>       <exsl:function name="set:intersection" override-builtin="true()">

I don't see this as necessary.  For instance, in 4XSLT I'd make such an 
optimization automatic.


-- 
Uche Ogbuji                               Principal Consultant
uche.ogbuji@fourthought.com               +1 303 583 9900 x 101
Fourthought, Inc.                         http://Fourthought.com 
4735 East Walnut St, Ste. C, Boulder, CO 80301-2537, USA
Software-engineering, knowledge-management, XML, CORBA, Linux, Python



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