RE: Ancestors and siblings

XPath 2.0 still has them and for XQuery they have been added as optional
in the last call draft. Why do you think they are gone?

Best regards
Michael

> -----Original Message-----
> From: www-ql-request@w3.org [mailto:www-ql-request@w3.org] On Behalf
Of
> Donald Spaeth
> Sent: Monday, May 24, 2004 6:42 AM
> To: www-ql@w3.org
> Subject: Ancestors and siblings
> 
> 
> I've just been reviewing the proofs of an article I wrote last year on
the
> use of XML to represent data derived from historical sources, and I
> realize
> that a passage on the many and wondrous uses of axes has been rendered
> obsolete by XPath 2.0 and XQuery.  Can someone explain why the
ancestor,
> preceding-sibling, and following-sibling axes have been dropped?
> 
> I found these axes useful in a couple of contexts.  My normal practice
(in
> XSLT) was to identify a unit of analysis and use for-each to iterate
at
> that
> level; I could then use ancestor to climb higher in the tree (or do I
mean
> lower?  closer to the root would be more accurate) and fetch data
which
> the
> current node had "inherited".  The sibling axes were handy for
proximity
> searches, so that I could study how objects were grouped together,
i.e.
> look
> at other leaves sharing the same stem.
> 
> I can see ways to achieve the same effect in XQuery, using let and
> position,
> but these seem rather roundabout.  If I can be permitted to quote
myself
> (!):  "XPath 'axes' provide the tools to study structural
relationships,
> navigating the genealogy-like hierarchy of XML data.  In addition to
the
> commonly-used axes of direct descent - ancestors, parents, children
and
> descendants - there are also axes for siblings, preceding and
subsequent
> elements, which by extension enable one to relate elements to their
> 'cousins
> '.  These tools are of most use when looking at how objects are
grouped
> together, enabling co-occurrence and sequence to be considered."
> 
> Michael Kay is on record as having argued for the preservation of
these
> axes.  Since he lost the debate, the arguments against them must have
been
> pretty persuasive.  What were they?  I gather from Michael Brundage's
> XQuery
> book that some implementations are keeping these axes although they
are
> not
> required to do so.  Why not just keep them within the specification?
> 
> Thanks,
> Donald Spaeth
> 
> Dr Donald Spaeth
> Senior Lecturer in Historical Computing
> Department of History
> 2 University Gardens
> University of Glasgow
> Glasgow  G12 8QQ
> 
> tel. 0141 330 3580
> reply to:  d.spaeth@history.arts.gla.ac.uk
>

Received on Monday, 24 May 2004 10:19:40 UTC