From mboxrd@z Thu Jan  1 00:00:00 1970
From: Myles English <mylesenglish@gmail.com>
Subject: wrong python version when using :session
Date: Mon, 05 Sep 2011 18:28:08 +0100
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To: emacs-orgmode@gnu.org

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