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Re: DOM Level 3 XPath updates really confusing me

From: Christian Parpart <cparpart@surakware.net>
Date: Sat, 22 Feb 2003 13:38:59 +0100
To: rayw@netscape.com (Ray Whitmer)
Cc: www-dom@w3.org
Message-Id: <200302221339.03627.cparpart@surakware.net>

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On Friday 21 February 2003 3:42 pm, Ray Whitmer inspired the electrons to say:
> Christian Parpart wrote:
[....]
> If you intend to follow the drafts so closely, change by change, I would
> suggest becoming a member of W3C and subscribing to the internal
> interest group lists where each technical decision is discussed.  The
> drafts which are publicly published typically are at longer intervals
> and, hence, are likely to contain a large number of fundamental changes.

I already took a look onto that page since this has really been my interest
for some time. I unfortunately have definitely _not_ that much money they
want from me. For the non-profit organization case (as this would apply to)
is twice as much as I get a year(!). With respect to the next bridge I would
have to live under when I really need to pay that is not my choice....
unfortunately.

> >The types SINGLE_NODE_TYPE and NODE_SET_TYPE are gone
> >and the following has been added:
> >     * UNORDERED_NODE_ITERATOR_TYPE,
> >     * ORDERED_NODE_ITERATOR_TYPE,
> >     * UNORDERED_NODE_SNAPSHOT_TYPE,
> >     * ORDERED_NODE_SNAPSHOT_TYPE,
> >     * ANY_UNORDERED_NODE_TYPE, and
> >     * FIRST_ORDERED_NODE_TYPE.
>
> The last-call document which also contained these major changes went
> into review over 10 months ago.  Working drafts are a work in progress,
> and you cannot expect to come back months later and have the
> specification be similar, necessarily, until it becomes a candidate
> recommendation or recommendation.

Of course, I just have a problem in imagination, I believe. When is what type
used. I mean, I previousely felt good with one node set type to handle any
node set. So, I'd probably got helped by giving me some use-cases for these
different node set types. (e.g. the XSLT document() function would return
just a single document node - FIRST_ORDERED_NODE_TYPE probably - and a
some/where expression would result in a ordered node set, I think. But what
about the other node set types? I didn't find a direct hint in the draft.

[....]
> >What about comparisons between all these new node types?
>
> These are not node types.  These are result types.  They have never been
> node types.

I was confused, sorry, I meant result types for the different node sets ;)

> >Also, the evaluate function does not take any parameter for
> >function/variable-scope. Why? This would be a nice way to extend the
> >function's provided as well as allow you easily to manipulate the
> > variables needed by the xpath expression of interest.
>
> On the one hand, it is not difficult to extend XPathEvaluator to permit
> this sort of thing, which we expect derived standards to do if they need
> to.  On the other hand, there are lots of complexities involved in
> completely providing this facility, which is why it was made out of
> scope very early on in the standard.  We tried to hit some form of the
> 80-20 rule.  There was no version of the specification ever published
> that provided this functionality.  That does not prevent custom
> functions and variables or even custom interfaces for adding functions
> and variables.

Well, it's IMHO more difficult to hide the function/variable scopes except you
do not want to provide the user with handling with user functions/variables.

> I hope this is helpful.
>
> Ray Whitmer
> rayw@netscape.com

It was ;)
Christian Parpart
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Received on Saturday, 22 February 2003 14:47:28 GMT

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