Execute src block on org mode export

Question

I have some sort of fundamental confusion about using src blocks in org mode.

I define a custom latex class in an emacs-lisp src block at the top of my org file. Export fails however, unless I manually execute the src block (because the required latex class doesn't exist until the src block is executed). I'm not prompted for permission to execute the block.

As a minimal example, I tried exporting this:

#+name: test
#+begin_src emacs-lisp
(message "Success")
#+end_src

On export, I see org-babel-exp processing... in my messages buffer, and I would expect to see "Success" immediately after it, but I don't.

I'm clearly missing something obvious, but it's not clear to me from the info what I should be doing.

Answer 1

The code blocks don't get evaluated unless you specifically tell Org mode to do it (or do C-h i g (org)Evaluating Code Blocks in Emacs). The snippet in your example will simply export to a code block in your chosen export format: pdf, html, etc.

More on Org mode and source blocks. (or do C-h i g (org)Working with Source Code in Emacs)

Here is the modified version of your example with the required #+CALL: line and the good to have buffer local variable declaration to mark the execution of emacs-lisp snippets as safe.

#+name: test
#+begin_src emacs-lisp
(message "Success")
#+end_src
  
#+call: test()

# Local Variables:
# org-confirm-babel-evaluate: (lambda (lang body) (not (string= lang "emacs-lisp")))
# End: