I am trying to find some ways to programatically modify org-elements that
use fewer regexps and motion commands. It seems like org-dp (
https://github.com/tj64/org-dp) was intended to do that but it is not clear
enough how you might use it, and it also doesn't seem to support
plain-lists yet.

What I imagined happening is that I would get the element to modify as a
data structure, modify the data structure, and replace the old element with
an interpreted version of the modified data structure.

I want to do something like a radio list where only one box can be checked
at a time. Suppose I have this:

#+attr_org: :radio
- [ ] one
- [ ] two
- [ ] three

It gets represented from org-element-context as:

(plain-list
 (:type unordered :begin 579 :end 630 :contents-begin 598 :contents-end 630
:structure
((598 0 "- " nil "[ ]" nil 608)
(608 0 "- " nil "[ ]" nil 618)
(618 0 "- " nil "[ ]" nil 630))
:post-blank 0 :post-affiliated 598 :attr_org
(":radio")
:parent nil))

What I thought I could is something like (here I simulate having point in
the first item):

#+BEGIN_SRC emacs-lisp :results code
(let* ((p 600) ;where current point is
       n
       (data '(plain-list
       (:type unordered :begin 579 :end 630 :contents-begin 598
:contents-end 630 :structure
      ((598 0 "- " nil "[ ]" nil 608)
       (608 0 "- " nil "[ ]" nil 618)
       (618 0 "- " nil "[ ]" nil 630))
      :post-blank 0 :post-affiliated 598 :attr_org
      (":radio")
      :parent nil)))
       (structure (plist-get (cadr data) :structure)))
  (loop for i from 0 for item in structure
do
(if (and (>= p (first item))
(< p (seventh item)))
    ;; in the item, toggle it
    (setf (fifth item) (if (string= "[X]" (fifth item))
   "[ ]"
"[X]"))
  ;; not on the item
  (setf (fifth item) "[ ]")))

  data)
#+END_SRC

Which outputs:

#+RESULTS:
#+BEGIN_SRC emacs-lisp
(plain-list
 (:type unordered :begin 579 :end 630 :contents-begin 598 :contents-end 630
:structure
((598 0 "- " nil "[X]" nil 608)
(608 0 "- " nil "[ ]" nil 618)
(618 0 "- " nil "[ ]" nil 630))
:post-blank 0 :post-affiliated 598 :attr_org
(":radio")
:parent nil))
#+END_SRC

As a step towards getting to a data structure I could programmatically
modify, and then reinterpret, I made this little function:

(defun ointerp ()
  (interactive)
  (let ((el (org-element-context)))
    (kill-new (org-element-interpret-data el))))

It works on some things, e.g. headlines, src blocks. I put the point on one
of those things, run this command, and then I can paste it somewhere to see
that it did indeed work.

But, it does not work on plain-lists, or paragraphs. I either get an empty
string, or Wrong type argument: char-or-string-p, nil

Is it possible to do what I am describing? Am I just missing how to get the
element data in the right form?

Thanks,



John

-----------------------------------
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu