Hi Babel I've been working on an exporter and have come across some strange behaviour regarding 'empty' source blocks with regard to tangling.
If an attempt is made to tangle a block containing two blank (no white-space) lines, the block is exported as carriage returns (as I would expect). If a block contains one or no blank lines, the #+end_src tag appears to be consumed by the block (along with subsequent text upto the next #+end_src tag). I tracked this down to the org-babel-src-block-regexp variable in ob.el and have modified it to give what appears to be consistent behaviour. I also found the following unresolved bug report which may be related... http://www.mail-archive.com/emacs-orgmode@gnu.org/msg29992.html I've included a simple test file, and resultant tangled files before and after the patch to attempt to convey the problem. NOTE: Since the patch itself modifies a defvar, and since I'm not clear on how a patched defvar should be updated downstream, the patch includes a setq statement to update the defvar org-babel-src-block-regexp for test purposes. The patch cannot therefore be applied as is.
* Empty Block Tangle Test
** Typical Execution
#+BEGIN_SRC emacs-lisp :tangle no
(org-babel-tangle) ; or org-babel-tangle-file "empty-block.org"
#+END_SRC
#+results:
| test-out |
** Tests
*** Block 1 (Exports OK)
#+BEGIN_SRC sh :tangle test-out
Block 1
#+END_SRC
*** Block 2 (Exports OK - double blank line no white-space in Block)
#+BEGIN_SRC sh :tangle test-out
#+END_SRC
*** Block 3 (Fails - single blank line no white-space in Block)
#+BEGIN_SRC sh :tangle test-out
#+END_SRC
*** Block 4 (Gets consumed by previous Block)
#+BEGIN_SRC sh :tangle test-out
Block 4
#+END_SRC
*** Block 5 (Fails - no lines in Block)
#+BEGIN_SRC sh :tangle test-out
#+END_SRC
*** Block 6 (Gets consumed by previous Block
#+BEGIN_SRC sh :tangle test-out
Block 6
#+END_SRC
*** Block 7 (Exports OK)
#+BEGIN_SRC sh :tangle test-out
Block 7
#+END_SRC
** List params
#+begin_src emacs-lisp
(sort* (mapcar (lambda (x)
(list (car x) (cdr x)))
params) 'string-lessp :key 'car)
#+end_src
#+results:
| :cache | no |
| :colname-names | nil |
| :colnames | no |
| :comments | |
| :exports | results |
| :hlines | yes |
| :noweb | no |
| :result-params | (replace) |
| :result-type | value |
| :results | replace |
| :rowname-names | nil |
| :session | none |
| :shebang | |
| :tangle | test-out |
test-out-pre-patch
Description: test-out-pre-patch
test-out-post-patch
Description: test-out-post-patch
diff --git a/lisp/ob.el b/lisp/ob.el
index 6e98263..6d2f0d0 100644
--- a/lisp/ob.el
+++ b/lisp/ob.el
@@ -138,9 +138,20 @@ remove code block execution from the C-c C-c keybinding."
;; (4) header arguments
"\\([^\n]*\\)\n"
;; (5) body
- "\\([^\000]+?\n\\)[ \t]*#\\+end_src")
+ "\\([^\000]*?\n*\\)[ \t]*#\\+end_src")
"Regexp used to identify code blocks.")
+(setq org-babel-src-block-regexp
+ (concat
+ ;; (1) indentation (2) lang
+ "^\\([ \t]*\\)#\\+begin_src[ \t]+\\([^ \f\t\n\r\v]+\\)[ \t]*"
+ ;; (3) switches
+ "\\([^\":\n]*\"[^\"\n*]*\"[^\":\n]*\\|[^\":\n]*\\)"
+ ;; (4) header arguments
+ "\\([^\n]*\\)\n"
+ ;; (5) body
+ "\\([^\000]*?\n*\\)[ \t]*#\\+end_src"))
+
(defvar org-babel-inline-src-block-regexp
(concat
;; (1) replacement target (2) lang
Regards Martyn --- Org-mode version 7.4 (release_7.4.529.gb23d) GNU Emacs 24.0.50.1 (i686-pc-linux-gnu, GTK+ Version 2.24.0) of 2011-02-25
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