[QGIS-Developer] Can't find SAGA devel versions after r413c6e5

[Alexander Bruy]

Hi Rainer,

2017-06-08 10:24 GMT+03:00 Rainer Hurling <rhurlin at gwdg.de>:
> For some reasons, we don't package our system with different versions of
> SAGA GIS. Recent FreeBSD comes with SAGA GIS version 3.0.0, I am working on
> an update to version 4.1.0.
>
> With your latest updates to QGIS (r413c6e5), newer versions of SAGA GIS than
> 2.3.x are not recognized any more :(
>
> I am familiar with the background, that QGIS processing only garantees to
> work well with the SAGA GIS LTR version. But there was a kind of tacit
> agreement for several years now, that QGIS processing tools also accepted to
> display (and somewhat work with) newer SAGA GIS versions.

Previously QGIS Processing supported multiple SAGA versions, but as SAGA
devs often changed API even between minor versions it was a real pain to
maintain compatibility and provide users with robust and working SAGA inteface.
Because for each change in SAGA API we need not only update algorithms
descriptions but also add some workaronds in the Processing source code.

After release of SAGA LTR we had several long discussions and finally decided
that better to have good support for single SAGA version that multiple partially
broken version. That's why support for all other versions was removed. We also
removed option to choose another SAGA installation, as this makes no sense
now and can lead to confusion in case when user select unsupported SAGA
version.

> Now my request: It would be fine and at least important for FreeBSD users,
> to have the possibility to use SAGA GIS > 2.3.x with QGIS 2.18.9 again.

I'm afrad this is not possible, as we have no resources to keep algorithms
descriptions and, more importantly, source code updated with numerous SAGA
API breaks in every SAGA release.

As an option I can suggest to create altenate SAGA provider plugin which will
support non-LTR SAGA versions.


-- 
Alexander Bruy