Re: Transitive closure for XPath

[Uche Ogbuji <uche.ogbuji@fourthought.com>]

> > something I really lose sleep over is the lack of a transitive closure
> > function in XPath. [...]
> > Would you please comment on a little proposal I have written -
includes
> > an implementation of the operator for Xalan as a freebie:
> >
> > http://www.cs.ucl.ac.uk/staff/c.nentwich/closure/
>
>
> This is indeed a very useful feature.
>
> The proposal as described slightly breaks the XPath evaluation
> model though: the second argument to 'closure(node-set,node-set)'
> has Algol-style call-by-name semantics.  That is, it's not really
> a node-set but rather an XPath expression or "thunk" which
> is re-evaluated with a different context multiple times.
> I think this calls for new syntax, either a new keyword or operator.

I'm sorry: I haven't looked closely at Christian's proposal, but based on
whay you say above, this might fall in with the dynamic programming
features under discussion for EXSLT (and that were earlier discussed on
xsl-list).


-- 
Uche Ogbuji                               Principal Consultant
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