How to include other .org files programmatically (ie not from main .org file)?

Question

Including other .org files is quite easy. For example, for configuration,

#+setupfile: /path/to/config.org

or

#INCLUDE: /path/to/config.org

Those lines need to be in the .org file in order to be processed.

How could one have a given #+setupfile and #+include file available programmatically at export time, without having to insert them in the file?

Practical use case: we need to batch process several hundreds org-mode files from a read-only repository. Those files do not have any #+setupfile and #+include file. For example, we need to make available a few #+MACRO lines (see below).

For each org-mode file, I could read it in a buffer, inject the needed #+setupfile and #+include, export the file, and go to the next.

Is there a simpler way, like for example setting #+setupfile or #+include as variables, so that they are automatically available at export time?

Perhaps there is a way to add something to .dir-locals.el?

We even though of using some elisp within org-load-hook or org-mode-hook, but I could not find a way to pass content that needs to be evaluated as active Org-mode.

Just to give an idea, this is a much simplified #+SETUPFILE:

#+OPTIONS: H:1 num:nil author:nil creator:nil timestamp:nil email:nil toc:t \n:nil @:t     ::t |:t ^:t -:t f:t *:t TeX:t LaTeX:nil skip:nil d:t tags:not-in-toc


#+MACRO: fleuron @@latex:\fleuron@@ @@html:<center>* * *</center>@@
#+MACRO: newline @@latex:\\@@ @@html:<br>@@ @@ascii:|@@

#+LATEX_CLASS: book
#+LATEX_CLASS_OPTIONS: [a4paper,twoside,onecolumn]
#+LATEX_HEADER: \bibliographystyle{plain}
#+LATEX_HEADER: \bibliography{bibliography}

Answer 1

Here's some code to work from. The key is use org-export-before-processing-hook.

(defcustom rasmus/setup-file '("/tmp/setup.org")
  "list of string with setup file or functions.

Functions must take care of keyword themselves and must return
strings.")

(defcustom rasmus/setup-file-keyword "#+INCLUDE: "
  "Keyword used by `rasmus/org-export-setup-files'")

(defun rasmus/org-export-setup-files (backend)
  "Include setup-files automatically.  

See also `rasmus/setup-file' and `rasmus/setup-file-keyword'"
  ;; TODO: Resolve local files.
  ;; TODO: Better control over where contents is inserted.
  (save-excursion
(goto-char (point-max))
(insert "\n"
 (mapconcat
  (lambda (elm)
    (cond ((stringp elm)
       (concat rasmus/setup-file-keyword elm))
      (functionp elm) (funcall elm)
      (t (error "`rasmus/setup-file' should contain only strings and functions!"))))
  rasmus/setup-file
  "\n"))))

(add-hook 'org-export-before-processing-hook
      'rasmus/org-export-setup-files)

And a test:

(progn
  (require 'ox-org)
  (find-file "/tmp/setup")
  (insert "this is setup!")
  (save-buffer)
  (kill-buffer)
  (with-temp-buffer
(insert "* test\n")
(org-org-export-as-org))

Output:

# Created 2015-01-16 Fri 16:37
#+TITLE: 
* test

This is the setup file

# Emacs 24.4.1 (Org mode 8.3beta)

Answer 2

Here's the basic idea:

(defun export-files-with-template (template sources)
  (cl-loop for file in (file-expand-wildcards sources)
           do (with-temp-buffer
                (insert-file template)
                (insert (format "#+include: %s\n" file))
                (org-mode)
                (let ((exported (org-export-as 'html))
                      (save-silently-p t))
                  (with-temp-file
                      (format "%s.html" (file-name-sans-extension file))
                    (insert exported))))))

(export-files-with-template "~/org/setupfile.org" "~/org/example/*.org")

The ~/org/setupfile.org is the file that contains macro and export setting definitions, ~/org/example/*.org are the files that need to be exported. You could, of course add more export backends / extend this to projects / specify output directory etc.; this is just the basic idea.