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Jeni Tennison scripsit:
> John brought up the issue of types that don't have total ordering. The
> lack of total ordering of durations and date/times with or without
> timezones has been a real pain in XPath 2.0 because for optimisation
> purposes you really need just one of $a = $b or $a != $b to be true.
> You could, of course, introduce three-valued logic to cope with the
> ambiguity, but I'd be interested if anyone had any other bright ideas.
IMHO the whole notion of times without zones is so much $*@(. The value
type should be just UTC instants or periods, and it should be possible
to specialize the type Date to the type ESTDate, or America_New_York_Date,
supplying the default timezone as part of the type.
The problem of incommensurable durations (which is longer, 60 sec or 1 min?)
is much more serious, and I don't see that anything can reliably be done
about it. Durations are simply not totally-ordered.
--
"Do I contradict myself? John Cowan
Very well then, I contradict myself. jcowan@reutershealth.com
I am large, I contain multitudes. http://www.ccil.org/~cowan
--Walt Whitman, _Leaves of Grass_ http://www.reutershealth.com
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