[GRASS-dev] GRASS & QGIS: the future

[Radim Blazek]

I have upgraded  the vector provider to GRASS 7, layers may be added
by drag from browser. The raster and the plugin are disabled. Be
careful about multiple versions on the same system
(LD_LIBRARY_PATH..., check with ldd if does not work).

Unfortunately GRASS 7 moved ahead towards its aim "to make life harder
for anyone trying to use the GRASS libraries" [1]. Basically more and
more low level functions are calling exit() instead of returning error
code if something failed. As I am not willing to implement GRASS
module call for each simple function, we have to think again about
hacks we can use:

1) add a requirement that GRASS 7 used with QGIS must be compiled with
-fexceptions

2) add a requirement that a patch (it is a single line comment in
fact) must be applied to GRASS 7 to make it usable with QGIS

3) use setjmp()/longjmp()

4) let QGIS crash whenever GRASS lib function fails

Radim

[1]https://trac.osgeo.org/grass/ticket/869#comment:1

On Thu, Mar 27, 2014 at 11:18 AM, Paolo Cavallini <cavallini at faunalia.it> wrote:
> Hi all.
> I learned during dinner that GRASS7 RC1 is due very soon. This opens the
> issue of its functioning in QGIS. IMHO:
>
> * the qgis-grass-plugin might stop working (this has to be tested)
> * some of the module options will be different
> * new modules will not be available in QGIS.
>
> I think we can deal with this in several ways:
>
> * dropping the plugin, and concentrate the work on Processing
> * upgrading both the plugin and Processing.
>
> In the first case, we have two major issues:
>
> * upgrading Processing GRASS modules
> * changing the current Processing behaviour, avoiding the import-export
> phase when piping consecutive GRASS commands; this makes GRASS modules
> slower than the equivalent commands of other backends.
>
> While the first issue can be solved easily by a couple of people in a
> few days, the second one is more tricky, and requires hard coding skills.
> In addition, we'll no longer be able to edit GRASS vectors directly.
>
> In the second case, we'll have more work, and a not-so-nice duplication.
>
> I would like to have an open discussion on this, avoiding things to just
> happen, with the possible negative consequences.
>
> All the best.
> --
> Paolo Cavallini - www.faunalia.eu
> QGIS & PostGIS courses: http://www.faunalia.eu/training.html
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