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RE: ORA-FO-UNORDERED 15.1.15 fn:unordered

From: Oliver Becker <obecker@informatik.hu-berlin.de>
Date: Wed, 24 Sep 2003 17:20:51 +0200 (MEST)
Message-Id: <200309241520.h8OFKpU5016226@mail.informatik.hu-berlin.de>
To: public-qt-comments@w3.org


> > I'm sorry, but I don't understand what the *function* 
> > fn:unordered really ought to do. 
> 
> Conceptually, fn:unordered returns an arbitrary permutation of its input
> sequence.
> 
> In reality, it tells the optimizer that it needn't go to the trouble of
> getting the input sequence in the right order, because the order isn't
> needed. So it's a true function in terms of the formal semantics, but is
> likely in practice to be treated as an optimization directive.

I'm not convinced that it is a good idea to disguise this as a function.

Can I expect that

<xsl:variable name="a" select="some-function()" />
<!-- perhaps do something with $a -->
<xsl:variable name="b" select="unordered($a)" />

and

<xsl:variable name="b" select="unordered(some-function())" />

will always give the same result sequence for $b?

I think it should result in the same sequence, but I can hardly
imagine how this should be implemented reasonably.

Oliver Becker

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|  ob|do        Dipl.Inf. Oliver Becker                             |
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Received on Wednesday, 24 September 2003 11:20:52 UTC

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