many thanks to both of you. Yours was very interesting to read, Thomas, but
ts makes it quite a bit easier to write:

(defun o-l-date-to-timestamp (date)
  "use ts.el date parse functions return an ISO-compatible
timestamp for transmission to Canvas via API. DATE is a string,
usually of the form `2019-09-26`, but optionally including a full time."

  (ts-format "%Y-%m-%dT%H:%M:%S%:z" (ts-parse-fill 'end date )))

I'm quite looking forward to using dash, s, ts, kv, etc to simplify my
often very obtuse legacy code.


On Sun, Sep 22, 2019 at 6:10 AM Thomas Plass <thunk2@arcor.de> wrote:

> Hi,
>
> Matt Price wrote at 16:27 on September 21, 2019:
> :
> : :DUE_AT: 2019-09-26
> :
> : ...
> :
> : I'm wondering though how hard
> : it would be to get the current time zone -- or the time zone that the
> course is taught in -- from
> : emacs, and construct the string from that value.
>
> This'll return the offset suffix (if that's what you want) when
> executed in your local time zone (presumably "-04:00"):
>
> (defun Price/local-time-offset-from-iso-date (y-m-d)
>   (let* ((ymd (mapcar (lambda (s) (string-to-number s)) (split-string
> y-m-d "-")))
>          (offsecs (nth 8
>                        (decode-time
>                         (apply #'encode-time
>                                (list 59 59 23 (nth 2 ymd) (nth 1 ymd) (nth
> 0 ymd)))))))
>     (format "%s%02d:%02d"
>             (if (> offsecs 0) "+" "-")
>             (/ offsecs 3600)
>             (% offsecs 3600))))
>
> On Unix, this'll always work.  On Windows, it works most of the time,
> but may fail in the weeks around switches from and to daylight saving.
>
> Thomas
>