[GRASS-dev] Handling of Python scripts on MS Windows

[Markus Metz]

On Mon, Feb 10, 2014 at 6:44 PM, Vaclav Petras <wenzeslaus at gmail.com> wrote:
>
>
>
> On Mon, Feb 10, 2014 at 8:41 AM, Markus Metz <markus.metz.giswork at gmail.com>
> wrote:
>>
>> On Mon, Feb 10, 2014 at 12:04 PM, Moritz Lennert
>> <mlennert at club.worldonline.be> wrote:
>> > On 10/02/14 11:46, Markus Metz wrote:
>> >>
>> >> On Mon, Feb 10, 2014 at 11:26 AM, Helmut Kudrnovsky <hellik at web.de>
>> >> wrote:
>> >>>>>
>> >>>>> Therefore we need
>> >>>>> hard-coded special treatment for shell and Python scripts in order
>> >>>>> to
>> >>>>> make sure that the correct interpreter is used.
>> >>>
>> >>>
>> >>>> Just for my understanding: When you say hard-coded special treatment
>> >>>> for
>> >>>> shell scripts, are you speaking about the .bat files ?
>> >>>
>> >>>
>> >>> I think yes.
>> >>
>> >>
>> >> Or more generally, any mechanism explicitly using %GRASS_PYTHON%
>> >> script.py.
>> >
>> >
>> > But as far as I've seen, this might not be sufficient since this only
>> > indicates which Python executable to use for launching the Python
>> > script,
>> > but any library calls linked to that execution will involve the
>> > system-wide
>> > installed Python. Which is different from bash scripts, where this is
>> > not an
>> > issue.
>>
>> GRASS Python scripts are currently executed using the system-wide
>> installed Python if it exists. No attempt has been made to explicitly
>> use GRASS_PYTHON, therefore it is not possible to say if the system's
>> Python would really be completely ignored.
>
>
> If I remember correctly, Python scripts were not working from Python
> scripts, they were working from command line.

Which command line? If you used the msys command line, it should work
because within msys, the embedded GRASS_PYTHON version is readily
available:

GRASS 7.0.svn> which python
/c/Programme/GRASS GIS 7.0.svn/extrabin/python.exe

> And we were not able to
> explain why the right Python (or Python DLL) is used at one point but not
> the other.

If you used the GUI, you are outside the msys shell and the system's
Python is used. Scripts invoke other GRASS modules with
grass.run_command() which uses the system's script interpreter if the
module is a script.

Markus M