[GRASS-dev] working on a add on to calculate MESS

[Glynn Clements]

Paulo van Breugel wrote:

> Hi Martin, thanks for the info. Only reason it is in grass 7 is because
> that is what I use (I find it works better for me than grass64). I can move
> it to grass 6, I probably need to make one or two small changes first
> (separator tag).
> 
> Although I appreciate that the preferred language is Python, is it in the
> plans to make it possible to install shell extensions using g.extension
> later on? For me, I unfortunately I don't know Python, and although I would
> love to work in Python, I simply do not have the time at the moment :-(

The main problem with using shell scripts in 7.0 is that they
typically won't work on Windows.

7.0 itself no longer requires a Unix shell or utilities to run; the
shell scripts have been replaced with Python versions, C code which
executes Unix utilities via system(), popen() etc has been re-written,
etc.

It is assumed that the Windows package for an eventual 7.0 release
won't include MSys, so a Unix shell and utilities won't necessarily be
available.

Also, Windows doesn't use a shebang (#!/bin/sh etc) to determine how
to run a script, it uses extensions. 6.x has some workarounds for
that, but those have been removed from 7.0 because they interfered
with running Python scripts.

OTOH, g.extension doesn't really work on Windows anyhow. Most users
won't have a compiler, make, or a Unix shell (which make requires). 
Windows users are better served by having extensions pre-compiled and
packaged.

-- 
Glynn Clements <glynn at gclements.plus.com>