Hi Karl

On Tue, May 17, 2016 at 9:54 AM, Karl Voit <devnull@karl-voit.at> wrote:

> Hi William
>
> * William Henney <whenney@gmail.com> wrote:
> >
> > On Sun, May 8, 2016 at 3:31 AM, Karl Voit <devnull@karl-voit.at> wrote:
> >
> > Python2 and Python3 are two different languages. Unfortunately,
> >> Org-mode only uses ~#+BEGIN_SRC python~ for both and uses
> >> python-shell-interpreter to choose/switch the compiler.
> >>
> >> Shouldn't Org-mode introduce ~#+BEGIN_SRC python2~ and ~#+BEGIN_SRC
> >> python3~ to solve this issue in a clean way?
> >>
> >> ~#+BEGIN_SRC python~ can still default to python2.
> >>
> > You can use the :python header argument to the source block, which allows
> > you to specify the path to the python interpreter:
> >
> > #+BEGIN_SRC python :python /Users/will/anaconda/envs/py27/bin/python
>
> Cool, I did not find this parameter yet.
>
> Is this undocumented? http://orgmode.org/org.html does not contain
> the string ":python:" and
> http://orgmode.org/org.html#Language_002dspecific-header-arguments
> also does not mention this parameter.
>
>
It is documented at
http://orgmode.org/worg/org-contrib/babel/languages/ob-doc-python.html

You are right that it would be better if the language-specific babel
documentation were better integrated in the general org info file.  But I
suppose nobody has been sufficiently motivated to do it yet


> > Also see original discussion at
> > https://lists.gnu.org/archive/html/emacs-orgmode/2014-04/msg01042.html
>
> Most interesting to me, thank you.
>
> With the parameter above as a workaround, I can accomplish the
> things I want to do for now. However, I still do think that Python2
> and Python3 as different languages demand different block
> identifiers.
>
> #+BEGIN_SRC python -> defaults to the default python interpreter
> #+BEGIN_SRC python2 -> uses Python2
> #+BEGIN_SRC python3 -> uses Python3
>
> Don't you think?
>
>
To be honest, I disagree that we need different block identifiers.  Python
is hardly the only language to have gone through multiple major versions,
and I don’t think a proliferation of org-babel languages is the answer.
What about C11 vs C99, etc?  I guess a good rule of thumb would be: do the
two versions use the same major mode in emacs?

Why is the :python parameter insufficient for your needs?  You can also use
it for different virtual environments

Cheers

Will



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-- 

  Dr William Henney, Instituto de Radioastronomía y Astrofísica,
  Universidad Nacional Autónoma de México, Campus Morelia