Re: [O] Limit subtree to a specific export backend

[Sebastian Wiesner]

2013/9/30 Rasmus <address@hidden>:
> Hi Sebastian,
>
> Sebastian Wiesner <address@hidden> writes:
>
>> can I limit a subtree to be exported with specific backends only?
>> I.e. only to HTML, but not Texinfo or LaTeX?
>>
>> Background:  I am trying to simplify the documentation of one of my
>> projects, and combine the website and the user manual into a single
>> document.  Naturally, there is some content on the website that should
>> not appear in the manual and vice versa.
>
> As Sebastien suggests, if you can identify export status depending on
> tags you can do it with a filter.

Great, I think I will go by this way…

I presume, I can set "org-export-filter-options-functions" as a
directory-local variable, so that this kind of export restrictions
only applies to Org mode documents in the specific project.

> Here's an example that's perhaps a bit too verbose and not thoroughly
> tested:
>
> #+BEGIN_SRC Org
> #+TITLE: Conditional export
> #+options: tags:nil
> * Common intro
>   txt
> ** Pdf heading                                                        :latex:
>    the math is really pretty!
> ** HTML heading                                                        :html:
>    the text features hyperlinks!
> ** More common notes
>    Intro over
>
> * Code                                                             :noexport:
> #+begin_src emacs-lisp
>   (defun rasmus/conditional-export (settings backend)
>     "Change SETTINGS to include dynamically set export-tags.
>
>     Enable the use of BACKEND as EXPORT_TAGS.  A derived backend is
>     treated as its parent."
>     (let ((backends (remove-duplicates
>                      (mapcar (lambda (x)
>                                (or (org-export-backend-parent x)
>                                    (org-export-backend-name x)))
>                              org-export--registered-backends)))
>           ;; for treating derived backend and parent backends differently:
>           ;; (backend-or-parent backend)
>           (backend-or-parent (dolist (b org-export--registered-backends 
> return)
>                                (when  (eq (org-export-backend-name b) backend)
>                                  (return (or (org-export-backend-parent b)
>                                              (org-export-backend-name b)))))))
>       (plist-put
>        settings :exclude-tags
>        (append (plist-get settings :exclude-tags)
>                (mapcar 'symbol-name
>                        (remove backend-or-parent backends))))))
>
>   (add-to-list 'org-export-filter-options-functions 
> 'rasmus/conditional-export)
> #+end_src
> #+END_SRC

Do I understand correctly, that this code adds all *other* backends to
the "exclude-tags" setting, instead of adding the current one to
"select-tags"?  Is there a specific reason to do this?

Just adding "backend" to "select-tags" seems simpler to me, and I
wonder whether "exclude-tags" even behaves correctly for headlines
with more than one tag.  As far as I understand the Org manual, it
would exclude headlines tagged as ":html:latex:" when exporting to
"html", because "latex" is added as exclude-tag, preventing the
headline from being exported.