Re: ISO date in attribution line

[lawrence mitchell <0198183+ding@sms.ed.ac.uk>]

Kai Grossjohann wrote:
> Andreas Fuchs <asf@void.at> writes:

>> ,----
>> | (defun sc-jk-normalize-date (date)
>> |   "Extract the date (day month year) from an RFC 822 message
>> | and write it as year-month-day (ISO 8601)"
>> |   (let ((date-list (cdr (cdr (cdr (parse-time-string date))))))
>> |     (let ((day (pop date-list)))
>> |       (let ((month (pop date-list)))
>> | 	(let ((year (car date-list)))
>> | 	  (and
>> | 	   year month day
>> | 	   (format "%d-%02d-%02d" year month day)))))))
>> `----

> I get the feeling that doing format-time-string on the result
> of parse-time-string would be enough.  Anyone want to try this?

> (defun sc-jk-normalize-date (date)
>   "..."
>   (let ((date (encode-time (parse-time-string date))))
>     (format-time-string "..." date)))

Elegant though it is, not quite, since encode-time doesn't like a
list, it wants each argument separetely, at least it does in 21.2
and 20.4, which is odd, since the doc-string claims that it's the
reverse of decode-time, which returns a list.  Hmm, I wonder if
this is a pseudo-bug.

Im any case, you can manage without quite as many let bindings as
Andreas used:
(defun sc-jk-normalize-date (date)
  (let ((date-list (cdddr (parse-time-string date)))
        day month year)
    (setq day (pop date-list)
          month (pop date-list)
          year (car date-list))
    (format "%d-%02d-%02d" year month day)))

However, I'm not sure if this isn't slower.

-- 
lawrence mitchell <0198183+ding@sms.ed.ac.uk>