Ken Mankoff <mankoff@gmail.com> writes:

> On Tue, 14 Jan 2014, Ken Mankoff wrote:
>>
>> I've seen various historical issues with :session but it seems I may have a
>> different problem. This is the latest org in emacs 24.3. If I do not have
>> :session, then everything works just fine.
>>
>> If I C-c C-c in the following code:
>>
>> #+BEGIN_SRC python :session transect
>> import numpy as np
>> x = np.arange(12)
>> #+END_SRC
>>
>> Emacs hangs the first time with minibuffer message of "Sent
>> python-eldoc-setup-code". If I C-g, I can edit the org buffer again. All
>> other invocations of that code and the minibuffer message is "executing
>> Python code block...", but still emacs hangs until I C-g.
>>
>
>
> Hmm. If I run IPython instead of regular python by setting this:
> (setq org-babel-python-command "ipython --pylab --pdb --nosep")
>
> Then org does not hang. It returns as expected. However, the
> capturing of output doesn't seem to work right.
>
> In Org, the following:
>
> #+begin_src python :session foo
> x = 42
> print x
> #+end_src
>
> Produces no RESULTS, and in the Python *foo* buffer I see:
>
> In [8]: x = 42
> In [9]: print x
> 42
> In [10]: open('/var/folders/60/jb7kfrsn2jd90hpcgj4m_wrc0000gn/T/babel-35562TZV/python-3$
> In [11]: 'org_babel_python_eoe'
> Out[11]: 'org_babel_python_eoe'
>
>
> But if I remove the "print" statment in Org:
>
> #+begin_src python :session foo
> x = 42
> x
> #+end_src
>
> Then the RESULTS shows me 42, and the Python *foo* buffer is:
>
> In [12]: x = 42
> In [13]: x
> Out[13]: 42
> In [14]: open('/var/folders/60/jb7kfrsn2jd90hpcgj4m_wrc0000gn/T/babel-35562TZV/python-3$
> In [15]: 'org_babel_python_eoe'
> In [15]: Out[15]: 'org_babel_python_eoe'

I believe that's the expected behaviour: the defaults value of :results
for python (and most other) source blocks is "value" and the print statement has no
value. If you want the output to appear in the results, try :results output.