On Wed, Sep 14, 2016 at 8:21 AM Clément Pit--Claudel <clement.pit@gmail.com>
wrote:

>
> Back when I wrote this I was starting out with Org-mode, I was in a hurry,
> and I didn't know about org-export-before-processing-hook :) So instead I
> had a larger ELisp script that opened the file, ran this filter, then
> called org-latex-export-to-latex :)
>

:)


> Looks good. Maybe using the same syntax for both would be good though;
> something like "BEGIN_ONLY tex" and "BEGIN_ONLY :not tex" maybe?
>

Thanks. I was exactly my earlier syntax idea but I scrapped it!


> We could probably get rid of the "tex" part after the END_ONLY, and change
> "tex" to "latex" for consistency with BEGIN_EXPORT :)


I thought of removing that too. But then thought of keeping it in case we
want to support nesting of these blocks.. I haven't yet needed to have
anything like this, but below is a rough idea.

#+BEGIN_EXCEPT tex
something
#+BEGIN_EXCEPT html
else
#+END_EXCEPT html
#+END_EXCEPT tex

I haven't tested this, but based on the code, nesting anyways doesn't work
as of now I believe.

Below is a modification of your code.

(defun cpit/filter-begin-only (type)
  "Remove BEGIN_ONLY %s blocks whose %s doesn't equal TYPE.
For those that match, only remove the delimiters.

On the flip side, for BEGIN_EXCEPT %s blocks, remove those if %s equals
TYPE. "
  (goto-char (point-min))
  (while (re-search-forward " *#\\+BEGIN_\\(ONLY\\|EXCEPT\\)
+\\([a-z]+\\)\n" nil t)
    (let ((only-or-export (match-string-no-properties 1))
          (block-type (match-string-no-properties 2))
          (begin-from (match-beginning 0))
          (begin-to (match-end 0)))
      (re-search-forward (format " *#\\+END_%s +%s\n" only-or-export
block-type))
      (let ((end-from (match-beginning 0))
            (end-to (match-end 0)))
        (if (or (and (string= "ONLY" only-or-export)
                     (string= type block-type))
                (and (string= "EXCEPT" only-or-export)
                     (not (string= type block-type))))
            (progn                      ; Keep the block,
                                        ; delete just the comment markers
              (delete-region end-from end-to)
              (delete-region begin-from begin-to))
          ;; Delete the block
          (message "Removing %s block" block-type)
          (delete-region begin-from end-to))))))
(add-hook 'org-export-before-process #'cpit/filter-begin-only)
-- 

Kaushal Modi