Re: Action 695 argument

On Tue, Feb 10, 2009 at 10:03 AM, Jos de Bruijn <debruijn@inf.unibz.it>wrote:

>
>
> Gary Hallmark wrote:
> >
> > Jos pointed out most of my "missing" builtins are actually there, in the
> > casting builtins.  I think we are missing maybe 2 builtins:
> >
> >   * How can I change a datetime from one timezone to another?
>
> There is indeed no built-in for that specific purpose.  However, one
> could extract all the components from a dateTime and construct a new
> one, e.g., using the string casting function.


xpath provides the following
        10.7.1 fn:adjust-dateTime-to-timezone<http://www.w3.org/TR/2007/REC-xpath-functions-20070123/#func-adjust-dateTime-to-timezone>
        10.7.2 fn:adjust-date-to-timezone<http://www.w3.org/TR/2007/REC-xpath-functions-20070123/#func-adjust-date-to-timezone>
        10.7.3 fn:adjust-time-to-timezone<http://www.w3.org/TR/2007/REC-xpath-functions-20070123/#func-adjust-time-to-timezone>


>
>
> >   * How do I reference the current datetime (e.g. fn:current-dateTime)?
>
> In a declarative formalism like BLD there cannot be such
> context-dependent things like "current" datetime, because then the
> formalism would not be declarative anymore.
> One would need to define the semantics relative to a context given by
> the user.  This would make things kind of ugly.


Semantically, fn:current-dateTime returns a literal dateTime D.  D is fixed
just prior to rule evalutation.  So if I evaluate some ruleset at
2009-02-10T00:00Z, then all references to fn:current-dateTime refer
to 2009-02-10T00:00Z.  If I subsequently evaluate the ruleset
at 2009-02-11T00:00Z, then all references to fn:current-dateTime refer
to 2009-02-11T00:00Z.  That shouldn't cause problems, I think.  It's how
SQL's SYSDATE works.

>
>
> I could imagine, though, that in PRD this would not really be a problem.
>  PRD does not need to restrict itself to the built-ins in BLD.
>
>
> Best, Jos
>
> >
> >
> > Gary Hallmark wrote:
> >>
> >>
> >>
> >> Dave Reynolds wrote:
> >>> So it sounds like you might need to propose that RIF adds xsd:date
> >>> and xsd:time (with and without timezone).
> >>>
> >> according to DTB, RIF already has xsd:date and xsd:time.
> >>
> >> why does xml schema add xsd:datetimestamp, but not add xsd:datestamp
> >> and xsd:timestamp that makes the timezone mandatory for dates and
> >> times as well as datetimes?
> >>
> >> It looks like DTB is incomplete in its support for date, time,
> >> datetime, and duration builtins.  For example,
> >>
> >>    * how can I construct a date from a string like "2009-02-09"?    *
> >> How can I construct a datetime from a date and a time?    * How can I
> >> split a datetime into a date and a time?    * How can I add a (int)
> >> number of hours to a datetime?
> >>    * How can I change a datetime from one timezone to another?
> >>    * How do I reference the current datetime (e.g. fn:current-dateTime
> >>      <#func-current-dateTime>)
> >>
> >>
> >
>
> --
> Jos de Bruijn            debruijn@inf.unibz.it
> +390471016224         http://www.debruijn.net/
> ----------------------------------------------
> No one who cannot rejoice in the discovery of
> his own mistakes deserves to be called a
> scholar.
>  - Donald Foster
>



-- 
Cheers,

Gary Hallmark