Re: wrong python version when using :session

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

Hi Myles,

The `org-babel-python-command' variable is used to decide which python
executable is used to run non-interactive python code.  Session
evaluation is performed using the interactive python mode defined in the
`org-babel-python-mode' variable.

,----
| org-babel-python-mode is a variable defined in `ob-python.el'.
| Its value is python
| 
| Documentation:
| Preferred python mode for use in running python interactively.
| This will typically be either 'python or 'python-mode.
| 
| [back]
`----

From there the selected interactive python back-end is responsible for
all python interaction and you would want to look at the relevant
documentation for that tool to find out how to specify which flavor of
python is used.

Hope this helps -- Eric

Myles English <mylesenglish@gmail.com> writes:

> Hello,
>
> When a python source block has a :session header argument, the python
> version selected does not appear to respect the value of the variable
> org-babel-python-command.
>
>
> Starting emacs with this in the init file (.emacs):
>
> (require 'org-install)
>
> (org-babel-do-load-languages
>  'org-babel-load-languages
>  '((python . t) ))
>
> (setq org-babel-python-command "python2")
>
>
> And in my org file:
>
> #+begin_src python :results output
> import sys
> print(sys.version)
> #+end_src
>
> #+results:
> : 2.7.2 (default, Jun 29 2011, 11:10:00) 
> : [GCC 4.6.1]
>
> Now, exactly the same but with ":session x" header argument:
>
> #+begin_src python :results output :session x
> import sys
> print(sys.version)
> #+end_src
>
> #+results:
> : 
> : 3.2.1 (default, Jul 11 2011, 12:37:47) 
> : [GCC 4.6.1]
>
> So babel has chosen to use Python 3.2 When I wanted to use Python 2.7,
> as in the first block, and the value of org-babel-python-command is
> still "python2".
>
> Part of the documentation for the variable python-python-command is:
> "Shell command to run Python interpreter".  On my system to run the
> Python 2.7 interpreter I would do:
>
> $ python2
>
> at the command line so, setting this variable thus:
>
> #+begin_src elisp
> (setq python-python-command "python2")
> #+end_src
>
> #+results:
> : python2
>
> and then using the two examples from above again gives the same
> (correct) results for the block without the :session header argument:
>
> #+begin_src python :results output
> import sys
> print(sys.version)
> #+end_src
>
> #+results:
> : 2.7.2 (default, Jun 29 2011, 11:10:00) 
> : [GCC 4.6.1]
>
> but a different error for the block with the session argument:
>
> #+begin_src python :results output :session x
> import sys
> print(sys.version)
> #+end_src
>
> results in the message:
>
> "python-check-version: Only Python versions >= 2.2 and < 3.0 are
> supported"
>
> Versions on my system are:
>
> orgmode commit cae9f947be (Aug 30th)
> GNU Emacs 23.3.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.22.1) of 2011-03-10 on bitzer.hoetzel.info
>
> $ ls -l `which python{2,3,}`
> /usr/bin/python -> python3
> /usr/bin/python2 -> python2.7
> /usr/bin/python3
>
> Am I doing something wrong or is this a bug?  I am wondering if it is
> reasonable to expect emacs/orgmode to be able to deal with the fact that I
> have Python 3 installed.
>
> Thanks,
>
> Myles
>

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