[O] [RFC] Add commmand for wrapping sexp/region in src-blocks to Org?

[Thorsten Jolitz]

Hi List, 

I often missed the following command for wrapping existing content into
src-blocks in the past, besides knowing about
`org-babel-demarcate-block' and easy template insertion. Would it make
sense to add it to Org-mode?

I made it cover several use cases:

  - Wrap sexp at point - perfect when on first paren of a nested list,
    or when a string should be wrapped in a programming-mode, or a
    word in a text-mode.

  - Wrap region between point and +/- N lines forward/backward (very
    fast because no point movement is involved).

  - Wrap active region.

Usage:

1. wrap active region or (if none) sexp-at-point in emacs-lisp src-block

,----
| M-x org-wrap-in-src-block       
`----

2. wrap active region or (if none) sexp-at-point in src-block, prompt
   user for Org-Babel language

,----
| C-u M-x org-wrap-in-src-block       
`----

3. prompt user for Org-Babel language and number of lines to wrap
(forward or backward)

,----
| C-u C-u M-x org-wrap-in-src-block       
`----


#+begin_src emacs-lisp
(defun org-wrap-in-src-block (&optional lang lines)
  "Wrap sexp-at-point or region in src-block.

Use Org-Babel LANGuage for the src-block if given, Emacs-Lisp
otherwise. A region instead of the sexp-at-point is wrapped if
either

   - optional argument LINES is an (positive or negative) integer
   - or the region is active

In the first case the region is determined by moving +/- LINES
forward/backward from point using `forward-line', in the second
case the active region is used. 

When called with prefix argument 'C-u', prompt the user for the
Org-Babel language to use. When called with two prefix arguments
'C-u C-u', prompt the user for both the Org-Babel language to use
and the number of lines to be wrapped."
  (interactive
   (cond
    ((equal current-prefix-arg nil) nil)
    ((equal current-prefix-arg '(4))
     (list
      (ido-completing-read "Org-Babel language: "
                           (mapcar
                            (lambda (--lang)
                              (symbol-name (car --lang)))
                            org-babel-load-languages)
                           nil nil nil nil "emacs-lisp")))
    ((equal current-prefix-arg '(16))
     (list
      (ido-completing-read "Org-Babel language: "
                           (mapcar
                            (lambda (--lang)
                              (symbol-name (car --lang)))
                            org-babel-load-languages)
                           nil nil nil nil "emacs-lisp")
      (read-number "Number of lines to wrap: " 1)))))
  (let* ((language (or lang "emacs-lisp"))
         (beg (or (and (not lines)
                       (region-active-p)
                       (region-beginning))
                  (point)))
         (marker (save-excursion (goto-char beg) (point-marker)))
         (bol (save-excursion (goto-char beg) (bolp)))
         (end (cond
               (lines (save-excursion
                        (forward-line lines) (point)))
               ((region-active-p)(region-end))
               (t (save-excursion
                    (forward-sexp) (point)))))
         (cut-strg (buffer-substring beg end)))
    (delete-region beg end)
    (goto-char (marker-position marker))
    (insert
     (format
      "%s#+begin_src %s\n%s%s#+end_src\n"
      (if (or (and lines (< lines 0)) bol) "" "\n")
      language
      cut-strg
      (if lines "" "\n")))
    (set-marker marker nil)))
#+end_src

-- 
cheers,
Thorsten