wrong python version when using :session

wrong python version when using :session

[Myles English]

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

Re: wrong python version when using :session

[Eric Schulte]

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/

Re: wrong python version when using :session

[Myles English]

Eric,

>> On Mon, 05 Sep 2011 11:35:37 -0600, Eric Schulte said:

  > 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.

The distinction had not occurred to me and of course it should have.

  > 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.

So for python-mode, the value of py-python-command decides the python
version:

(setq org-babel-python-command "python2"
      org-babel-python-mode 'python-mode
      py-python-command "python2"
)

  > Hope this helps -- Eric

It did, thank you very much.

Myles