Re: [PATCH v4] org-encode-time compatibility and convenience helper

[Max Nikulin]

On 11/05/2022 20:20, Ihor Radchenko wrote:
> Max Nikulin writes:
>
> > > +              ;; In Emacs-27 and Emacs-28 `encode-time' does not support 6 
> > > elements
> > > +              ;; list argument so `org-encode-time' can not be outside of 
> > > `pcase'.
> > > +              (pcase-let
> > > +                  ((`(,_ ,_ ,_ ,d ,m ,y ,dow . ,_) (decode-time start)))
> > > +                (pcase step
> > > +                  (`day (org-encode-time 0 0 org-extend-today-until (1+ d) m 
> > > y))
> > > +                  (`week
> > > +                   (let ((offset (if (= dow week-start) 7
> > > +                                   (mod (- week-start dow) 7))))
> > > +                     (org-encode-time 0 0 org-extend-today-until (+ d offset) 
> > > m y)))
> > > +                  (`semimonth (org-encode-time 0 0 0
> > > +                                               (if (< d 16) 16 1)
> > > +                                               (if (< d 16) m (1+ m)) y))
> > > +                  (`month (org-encode-time 0 0 0 month-start (1+ m) y))
> > > +                  (`year (org-encode-time 0 0 org-extend-today-until 1 1 (1+ 
> > > y))))))
> >
> > I do not like repeating of `org-encode-time' but do not see another way
> > till Emacs-29 will become the lowest supported version.
>
> This is fine. AFAIK, other parts of time handling code is full of conds
> and pcases.

I mean that before my patch there was single `encode-time' outside of 
`pcase', I replace `list' by `org-encode-time' inside each pattern.

> > > +           (org-encode-time
> > > +             (apply #'list
> > > +                    (or (car time0) 0)
> > > +                    (+ (if (eq timestamp? 'minute) n 0) (nth 1 time0))
> > > +                    (+ (if (eq timestamp? 'hour) n 0)   (nth 2 time0))
> > > +                    (+ (if (eq timestamp? 'day) n 0)    (nth 3 time0))
> > > +                    (+ (if (eq timestamp? 'month) n 0)  (nth 4 time0))
> > > +                    (+ (if (eq timestamp? 'year) n 0)   (nth 5 time0))
> > > +                    (nthcdr 6 time0))))
> > >         (when (and (memq timestamp? '(hour minute))
> > >                  extra
> > >                  (string-match "-\\([012][0-9]\\):\\([0-5][0-9]\\)" extra))
> >
> > I am tempting to write something like
> >
> >     (let* ((ts (copy-sequence time0))
> >          (ord (memq timestamp? '(year month day hour minute)))
> >          (field (and ord (nthcdr (length ord) ts))))
> >       (when field
> >         (setcar field (+ (car field) n)))
> >       (org-encode-time ts))
> >
> > but I am afraid it will make the code rather obscure.
>
> Yes, the second version is rather hard to understand. The proper
> solution would be writing (or using) some high-level time handling
> library and then using it in Org. Then, we would not need to deal with
> low-level time representations so frequently.

From my point of view

  (cl-mapcar
   (lambda (value part)
     (if (and part (eq part timestamp?))
         (+ n value)
       value))
   time0 '(second minute hour day month year nil nil nil))

is better than the original code, but...

Nicolas Goaziou to emacs-orgmode. [Patch] to correctly sort the items 
with emphasis marks in a list. Mon, 19 Apr 2021 18:08:17 +0200.
https://list.orgmode.org/87r1j6b6ku.fsf@nicolasgoaziou.fr
>
> I stay away from CL as much as possible, otherwise newcomers will have
> to learn two languages to start contributing, Elisp and CL (cl-loop,
> ewww). CL is still necessary however, as we cannot use `seq' yet.