Re: Fwd: run python from org, draft

[Eric Schulte <schulte.eric@gmail.com>]

Andreas Röhler <andreas.roehler@easy-emacs.de> writes:

> Am 29.03.2013 16:09, schrieb Eric Schulte:
>>>> with current
>>>>
>>>> GNU Emacs 24.3.1 (i686-pc-linux-gnu, GTK+ Version 2.24.14) of 2013-03-05
>>>>
>>>> Org-mode version 7.9.3f (release_7.9.3f-17-g7524ef @
>>>> MY_PATH/emacs-24.3/lisp/org/)
>>>>
>>>> python from org-source seems completely broken.
>>>>
>>>> For example:
>>>>
>>>> #+BEGIN_SRC python
>>>> 1+2
>>>> #+END_SRC
>>>>
>>>> #+RESULTS:
>>>> : None
>>>>
>>>>
>>> Weird. With all the testing we did last week, I'm surprised that this is
>>> the case with me as well. I'm also getting no results with Org 8.0-pre and
>>> Emacs 24.3.1.
>>>
>>
>> Because of quirks of the python language,
>
> or rather the quirks of org-babel? ;)
>
>   when executing outside of a
>> session, it is necessary to explicitly specify a return.
>>
>> For example.
>>
>>      #+begin_src python
>>        return 1+2
>>      #+end_src
>>
>>      #+RESULTS:
>>      : 3
>>
>> or
>>
>>      #+begin_src python :return x
>>        x = 1+2
>>      #+end_src
>>
>>      #+RESULTS:
>>      : 3
>>
>> This is clearly stated in the Python documentation on Worg.
>> http://orgmode.org/worg/org-contrib/babel/languages/ob-doc-python.html
>>
>> Thanks,
>>
>
> IMO org-babel should be able to run source code as is.

A valid opinion, in fact I think I defended that point of view myself,
and we used to wrap python code in a function so that we could easily
return the result of the block without an explicit return statement.
However people who use Python more than myself argued for the current
behavior and made a convincing point.  Please look back through the
mailing list archives to see the discussion if you're not convinced.

> 
> If an org-mode specific modification is required at such a trivial
> form, what to expect wrt complex environments?
>

People have been using Org-mode's code block support for years, often in
complex environments.  However they tend to get along better if they
read the documentation.

>
> BTW this fails also:
>
> #+begin_src python
> print "Hello, world!"
> #+end_src python
>
> #+RESULTS:
> : None
>

Because it does not return any value, and you are asking for the value,
if you add ":results output" to the header of that code block you'll get
what you appear to expect.  I acknowledge that there are a host of
header arguments and things to learn (value vs. output, language
specific quirks etc...) to enable sophisticated use of code blocks in
Org-mode.  The best way to learn this stuff is through the
documentation, *not* through repeatedly sending non working examples to
the mailing list.

>
>
> Can't see a consistent behavior so far.
>
> Why not follow the path given, which avoids the artistics?
>

I don't understand this last sentences at all.

>
>
> Andreas
>
>
>

-- 
Eric Schulte
http://cs.unm.edu/~eschulte