[iterate-devel] date iterator extension to iterate

[Venkatesan S]

> Well, using something other than a plain symbol after the FOR keyword
> isn't supported by DEFMACRO-DRIVER because that symbol is inserted in a
> normal macro definition.  E.g.:
>
> yeah, I saw it in macroexpand and the macro flew into a rage if I tried to
use any other variable than the first in the next form (like: (,kwd ,mm ...
). I ascribed it to my lack of knowledge and never thought it was illegal
:)


> Well, contact the author?  And although it may for you logically belong
> there, it adds a dependency to the date-calc package, which is, for a
> small library perhaps not worth it.  Since iterate has contribs (or one,
> the postgres driver) I'd think it could be added there instead more
> easily.  But I'm only using this library, so same goes here.
>
> I posted to date-calc-devel mailing list too, but as you say contribs might
be a better place for this. How do I go about putting this into
iterate/contribs?


Thanks for your time, and the inputs. I very much appreciate it.

Code remarks: I'd probably use &key instead of &optional, because
> wrapping date-calc:today every time I want to change skip-weekends would
> be too much work.  Everything else is personal style, such as my habit
> for long names.  And for just learning it looks good, imho.
>
> General remarks: use irc.freenode.net, #lisp and, if you like usenet,
> comp.lang.lisp, because there're certainly more people reading in those
> places.  And you'll get more flames ;)
>
> Cheers,
> Olof
>
> [1]: http://www.lispworks.com/documentation/HyperSpec/Body/03_dd.htm
>
> --8<---------------cut here---------------start------------->8---
> (iterate::defclause-driver (FOR year-month-date-vars FROM-DATE
> from-date-spec &optional TO to-date-spec BY (n 1) SKIP-WEEKENDS (skipval t))
>  "Driver for iterating over dates.  All dates are in (YYYY MM DD) format."
>  (declare (ignorable to-date-spec))
>  (iterate::top-level-check)
>  (unless (and (listp year-month-date-vars)
>               (every #'symbolp year-month-date-vars))
>    (iterate::clause-error "~a should be a list of up to three variables: ~
> the year, month and day" year-month-date-vars))
>  (mapc #'iterate::make-default-binding year-month-date-vars)
>  (let* ((step-var (iterate::make-var-and-default-binding 'by :type
> 'fixnum))
>         (fy (iterate::make-var-and-default-binding 'from-year :type
> 'fixnum))
>         (fm (iterate::make-var-and-default-binding 'from-month :type
> 'fixnum))
>         (fd (iterate::make-var-and-default-binding 'from-day :type
> 'fixnum))
>         (ty (iterate::make-var-and-default-binding 'to-year :type 'fixnum))
>         (tm (iterate::make-var-and-default-binding 'to-month :type
> 'fixnum))
>         (td (iterate::make-var-and-default-binding 'to-day :type 'fixnum))
>         (step `((multiple-value-setq (,fy ,fm ,fd)
>                   (get-next-day ,fy ,fm ,fd ,step-var ,skipval))
>                 (multiple-value-setq ,year-month-date-vars
>                   (values ,fy ,fm ,fd))))
>         (test `(when (< (date-calc:delta-days ,fy ,fm ,fd ,ty ,tm ,td) 0)
>                  (go ,iterate::*loop-end*))))
>    (setf iterate::*loop-end-used?* T)
>    (iterate::return-driver-code
>     :initial `((setq ,step-var ,n)
>                (destructuring-bind (y m d)
>                    ,from-date-spec
>                  (multiple-value-setq (,fy ,fm ,fd)
>                    (get-next-day y m d (- ,step-var) ,skipval)))
>                (let ((spec ,to-date-spec))
>                  (multiple-value-setq (,ty ,tm ,td)
>                    (if spec
>                        (values-list spec)
>                        (date-calc:today)))))
>     :next `(,.step ,test)
>     :variable year-month-date-vars)))
> --8<---------------cut here---------------end--------------->8---
>
> --
> The world is burning.  Run.
>
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-- 
Audentis fortuna juvat
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