[Qgis-developer] Proposal: Having all Processing providers as independent components

[Nyall Dawson]

On 6 December 2016 at 18:25, Victor Olaya <volayaf at gmail.com> wrote:

>
>> It might be a way full of caveats probably. Also, does that fit with the
>> idea from Matthias and Nyall of having core processing capabilities to have
>> them enabled in Android (or any python unfriendly platform) ?.
>>
>
> I like that idea very much (i have to reply to that email, BTW...),
> and this is not a problem. Functionality will be put into core and
> then wrapped by Processing. Most likely that core functionality, when
> exposed through Processing, will be added to the native QGIS
> Processing provider, so it will be a core stuff in Processing as well.
> And if not, the functionality will be there in QGIS, although not
> exposed through Processing, but the user could add the corresponding
> provider easily
>
> About the idea of putting core classes like GeoAlgorithm, etc in core,
> this should no affect that at all.

Agreed.

Slightly off topic, but I'm not sure (yet) if we should port the
actual algorithms themselves to c++. For my purposes (Matthias might
disagree here) it would be sufficient to allow algorithms to be fully
created in c++ only if required. Otherwise, I quite like having the
algorithms themselves as small python wrappers around inbuilt
functionality.

What I *would* like to see is for all the "heavy lifting" to be moved
out of the python algorithms and into the corresponding c++ classes.
Eg for an algorithm like the minimum oriented bounding box alg the
geometry operations should be moved to QgsGeometry and the algorithm
just become a lightweight wrapper around this functionality. IMO this
approach has numerous benefits, including speed and better
re-usability both within processing and with other plugins. I
personally think it's also nice for most of these operations to be
available as expression functions so that they can be used in
symbology, labeling, geometry generators etc.

Nyall


>
> Thanks for your ideas!
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