Andreas Leha <andreas.leha@med.uni-goettingen.de> writes:

> Hi Eric,
>
>
> Eric Schulte <schulte.eric@gmail.com> writes:
>
>> Hi Andreas,
>>
>> This should be easy to turn on or off using the newly introduced
>> :prologue and :epilogue header arguments.  See the manual and the
>> following example.
>>
>> #+Title: debug messages
>> #+Property: session *R*
>> #+Property: prologue (format "print(\"entering %s\")" (get-current-name))
>>
>> An elisp block to simplify the =:prologue= definition.
>> #+begin_src emacs-lisp
>>   (defun get-current-name ()
>>     (save-excursion
>>       (goto-char org-babel-current-src-block-location)
>>       (while (and (forward-line -1)
>>                   (looking-at org-babel-multi-line-header-regexp)))
>>       (when (looking-at org-babel-src-name-w-name-regexp)
>>         (org-no-properties (match-string 3)))))
>> #+end_src
>>
>> Two blocks with simple assignments.
>>
>> #+name: block-1
>> #+begin_src R
>>   x <- 2 + 2
>> #+end_src
>>
>> #+name: block-2
>> #+begin_src R
>>   y <- x + x
>> #+end_src
>>
>> Execute the whole buffer =C-c C-v b= to see the prologue in action.
>>
>> Andreas Leha <andreas.leha@med.uni-goettingen.de> writes:
>>
>>> Hi all,
>>>
>>> I would love to see messages like 'entering block foo...' and
>>> '...leaving block foo' printed to my R console.  This would be very
>>> handy when I evaluate a subtree (C-c C-v s) with a lot of #+call lines
>>> and some lengthy ones.
>>>
>>> I know that
>>> (1) I could implement that myself at in the source blocks.  But I would
>>>     love if orgmode did that for me
>>> (2) Such messages are already printed to the emacs *Messages* buffer.
>>>     But that buffer might not be visible and I can not switch to it,
>>>     without interrupting the evaluation.  Anyway it would be much nicer
>>>     to see that output together with the other output, that my code
>>>     generates.
>>>
>>>
>>> In essence it would be very helpful, if there was a variable
>>> org-babel-print-debug-messages (or org-babel-debug-level...) which if
>>> non-nil would cause that messages to be printed.  Or is there somewhere
>>> already?
>>>
>>> Regards,
>>> Andreas
>>>
>>>
>>>
>>>
>
>
> thanks for the quick answer!  The :prologue and :epilogue header
> arguments have indeed slipped my attention and they look really
> interesting!  I see, that they are documented, but somehow, they seem to
> not get their headline and TOC entry?
>
> I have three problems with your example, though:
> 1) It does not run
> 2) It does not work
> 3) It won't be usable for 'my' epilogue, correct?
> ;-)
>

Ah! My fault.  I had to add prologue and epilogue support to ob-R.el
when working through the example I sent, but then I forgot to commit
that support to Org-mode.  I've just pushed up that commit, and
re-worked my example file to avoid the issue of prologue being applied
to the emacs-lisp code block (using the very nice and also new
language-specific PROPERTY header arguments).

Finally, I don't use epilogues in the example because (as the last thing
evaluated) they would override the code block results.

Hopefully the following:
1. will run
2. will work
3. will be usable

Cheers,