But it occurs to me that in this case the expressions are functionally
identical: the set of predicates is effectively an AND group.
Is there any reason to prefer one form expression over the other?
No, but the ordering of the sub-expressions (assuming the processor
does shortcuts) can be really important. That is, place first the
sub-expression that most-often would make the whole expression false()
(in case of "and"-ing) or true() (in case of "or"-ing).
I believe that shortcutting isn't specified as mandatory in the XPath
specifications, but I might be wrong. Certainly, any serious optimizer
will do shortcutting.
Cheers,
Dimitre
On Tue, Feb 21, 2017 at 2:07 PM, Eliot Kimber ekimber(_at_)contrext(_dot_)com
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
I’m updating code that has expressions like:
<xsl:when test=”*[@a = ‘1’ and @b = ‘2’ and @c = ‘3’]”>
My normal practice would be to use separate predicates:
<xsl:when test=”*[@a = ‘1’][@b = ‘2’][@c = ‘3’]”>
But it occurs to me that in this case the expressions are functionally
identical: the set of predicates is effectively an AND group.
Is there any reason to prefer one form expression over the other?
I can imagine that different XSLT processors might apply different
optimization strategies to the two forms, although as we’ve discussed many
times, that’s not something you can worry about for general usage.
Cheers,
Eliot
--
Eliot Kimber
http://contrext.com
--
Cheers,
Dimitre Novatchev
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Truly great madness cannot be achieved without significant intelligence.
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To invent, you need a good imagination and a pile of junk
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Never fight an inanimate object
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To avoid situations in which you might make mistakes may be the
biggest mistake of all
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Quality means doing it right when no one is looking.
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You've achieved success in your field when you don't know whether what
you're doing is work or play
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To achieve the impossible dream, try going to sleep.
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Sanity is madness put to good use.
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I finally figured out the only reason to be alive is to enjoy it.
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