[xquery-talk] Extend and override

Tim Finney tjf at tfinney.net
Wed Aug 10 12:15:44 PDT 2011

Hi Michael,

Thank you for your reply. It helps me know that there is no obvious

A philosophical question with no need for an answer: What is the
distance between XQuery 3.0 and Lisp?


Tim Finney

On Wed, 2011-08-10 at 18:30 +0100, Michael Kay wrote:
> On 10/08/2011 17:02, Tim Finney wrote:
> > Hi Everyone,
> >
> > I'm interested to know how to do extension and override.
> With XSLT ;-)
> Seriously, I did a consultancy assignment with a big XQuery user and 
> this was a major hassle. We invented some kind of machinery for building 
> a query using variant versions of a library module to handle different 
> scenarios, but we had to decide up front which version of the query to 
> use in each run-time situation so it wasn't much fun.
> >
> > Can it be done in an elegant and bomb proof way? I'd like to know
> > whether any of you know about good general approaches in this area.
> >
> In XQuery 3.0 we have dynamic function items and some of us still have 
> hopes that we might get maps. (If maps aren't in the standard, they will 
> certainly be in many implementations). With a map of function items you 
> have something akin to a weakly-typed object as in Javascript, and you 
> can use it to do dynamic despatch. It doesn't provide all that you are 
> asking for, but at least there is no longer a brick wall.
> Michael Kay
> Saxonica
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