Argh, wish I could delete this post.  I was using a defective macro
definition (I pasted the wrong code in my original post!):

(defun get-ts+7 ()
  (interactive)
  (let ((base-date (save-excursion
               (re-search-backward
                (org-re-timestamp 'all))
               (match-string 0)))
        (result nil))
    (with-temp-buffer
      (org-mode)
      (insert base-date )
      (backward-char)
      (org-timestamp-change 7 'day)
      (end-of-buffer)
      (insert "  ")
      (end-of-buffer)
      (setq result (save-excursion
                     (re-search-backward
                      (org-re-timestamp 'all))
                     (match-string 0))))
    result))

--
something about that buffer switching gets org confused -- maybe the value
of hte {{{n}}} gets reset when the temp buffer is initialized? -- anyway,
this much simpler defun solves the problem:

(defun get-ts+7 ()
    (interactive)
    (let ((base-date (save-excursion
                 (re-search-backward
                  (org-re-timestamp 'all))
                 (match-string 0)))
          (result nil))

      (format-time-string "<%Y-%m-%d %a>"
                          (time-add
                           (date-to-time base-date) (days-to-time (1+ 7))))
))


On Sat, Aug 26, 2017 at 5:09 PM, Matt Price <moptop99@gmail.com> wrote:

>
> the {{{n}}} macro seems to reset to "1" if it is located on the same line
> as another macro that I've defined.  I'm not sure if it's error with my
> macro or some kind or race condition-ish problem in macro expansion.
> Here's a minimal example:
>
> --------
> #+MACRO: ts (eval (get-ts+7))
>
> #+BEGIN_SRC emacs-lisp
>   (defun mwp-add-week-to-next-ts ()
>     (interactive )
>     (save-excursion
>       (re-search-forward org-ts-regexp)
>
>       (let ((base (match-string 0)))
>         (message base)
>         (message (format-time-string "<%Y-%m-%d %a>"
>                                      (time-add (date-to-time base)
> (days-to-time (1+ 7)))))
>
>         (replace-match (format-time-string "<%Y-%m-%d %a>"
>                                            (time-add (date-to-time base)
> (seconds-to-time (1+(* 7 60 60 24))))) nil nil nil nil))))
> #+END_SRC
>
> (week {{{n(w)}}})
>
> (week {{{n(w)}}})
>
> (week {{{n(w)}}})
>
>
> ** <2017-09-12 Tue> (Week {{{n(w)}}}) Hacking History in the Himalaya
>
> ** {{{ts}}} (Week {{{n(w)}}}) Language of the Web
>
> -----------------
>
> And here's the ASCII export:
>
> ------
> Matt Price
>
>
> ,----
> | (defun mwp-add-week-to-next-ts ()
> |   (interactive )
> |   (save-excursion
> |     (re-search-forward org-ts-regexp)
> |
> |     (let ((base (match-string 0)))
> |       (message base)
> |       (message (format-time-string "<%Y-%m-%d %a>"
> |                                    (time-add (date-to-time base)
> (days-to-time (1+ 7)))))
> |
> |       (replace-match (format-time-string "<%Y-%m-%d %a>"
> |                                          (time-add (date-to-time base)
> (seconds-to-time (1+(* 7 60 60 24))))) nil nil nil nil))))
> `----
>
> 1
>
> 2
>
> 3
>
>
> <2017-09-12 Tue>  (Week 4) Hacking History in the Himalaya
> ==========================================================
>
>
> <2017-09-19 Tue>  (Week 1) Language of the Web
> ==============================================
> -----------------
>
> Any thoughts? thank you!
>
>
>