Conditionally evaluate scattered source code blocks in org mode

Question

I have an org document with various source code blocks. Some of blocks should be evaluated conditionally on org-babel-execute-buffer; however, these blocks are scattered throughout the document, which means I'm not able to set :eval no under a single heading and call it a day.

I've attempted to do this via a property, but the following fails and both blocks are evaluated:

#+PROPERTY: maybe-eval no

#+BEGIN_SRC emacs-lisp :eval yes
(message "want this block evaluated")
#+END_SRC

#+BEGIN_SRC emacs-lisp :eval (org-entry-get nil "maybe-eval" t)
(message "don't want this block evaluated but to my chagrin it happens anyway")
#+END_SRC

Is it possible to use properties like this or is there another way to achieve the same behavior?

Answer 1

You have the wrong function: you want org-entry-get, not org-get-entry. Use C-h f <function name> to read about each one.

If I do M-x org-babel-execute-buffer on your example (after the correction), I get this:

#+PROPERTY: maybe-eval no

#+BEGIN_SRC emacs-lisp :eval yes
(message "want this block evaluated")
#+END_SRC

#+RESULTS:
: want this block evaluated

#+BEGIN_SRC emacs-lisp :eval (org-entry-get nil "maybe-eval" t)
(message "don't want this block evaluated but to my chagrin it happens anyway")
#+END_SRC

The second is not evaluated and I get a message in the echo area:

Evaluation of this emacs-lisp code block is disabled.

If you have just added the #+PROPERTY line in the buffer, the property is not known until you do one of three things:

• press C-c C-c on the #+PROPERTY line (or any such keyword line)

• do M-x normal-mode to reestablish the mode and activate all keyword lines

• save and kill the buffer and reopen the file

This might be the reason that you thought that it didn't work. Also, be sure to delete old results before M-x org-babel-evaluate-buffer: they don't go away on reevaluation, so that might also fool you into thinking that it did not work.