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

[Markus Metz]

On Mon, Jan 27, 2014 at 12:16 AM, Glynn Clements
<glynn at gclements.plus.com> wrote:
>
> Markus Metz wrote:
>
>> On Sat, Jan 25, 2014 at 3:59 PM, Helena Mitasova <hmitaso at ncsu.edu> wrote:
>> > Just a note, given that most of these problems were caused by conflicts with python installed by ArcGIS,
>> > I checked with our GIS support and the latest ArcGIS 10.2 installs python2.7 which (I guess) should work with GRASS.
>>
>> No, there are different versions of Python 2.7, and not all work with
>> GRASS, see e.g. ticket 2015
>
> Any version of Python 2.7 should be suitable for GRASS.

Not all versions of Python 2.7 are suitable for WinGRASS, see ticket #2150.

> However, it
> needs to be installed correctly, and GRASS needs to not attempt to
> bundle Python.
>
>> GRASS should not use a system-wide Python installation, or more
>> precisely, should explicitly ignore any system-wide python file
>> associations. Expecting system-wide python file associations is the
>> cause of all the trouble.
>
> "Executing" a script uses the registry associations for the script's
> extension.

WinGRASS does not set registry associations for Python scripts, nor
does it install Python system-wide. This is because we do not want to
modify an existing Python installation.
>
> Attempting to by-pass the system's script execution mechanism (by
> explicitly executing Python scripts via a specific interpreter) is the
> cause of all the trouble.

I disagree. Troubles arise if the system's interpreter, e.g. Python
installed by ArcGIS, is used instead of the python version embedded in
WinGRASS.

Markus M