[Qgis-developer] virtual fields

Matthias Kuhn matthias.kuhn at gmx.ch
Mon Mar 3 13:09:28 PST 2014

On Mon 03 Mär 2014 17:55:06 CET, Denis Rouzaud wrote:
> On 03. 03. 14 16:42, Matthias Kuhn wrote:
>> On a similar note see this recent thread [1] which should be able to
>> provide this kind of functionality. I don't know if Nahtan has
>> already started to implement his POC.
> What would be the advantage of such a beast?
> Is it the caching?

Not sure about dis- and atvantages. I just thought I'd throw it in :-)

Honestly: injecting expression fields at the vectorlayeriterator level 
sounds like a good and flexible approach. There are quite a few tools 
which still operate on vlayer.provider.getFeatures() etc. Those will 
unfortunately not be able to benefit from such an approach.
The virtual layer approach discussed in the other thread is more like a 
Swiss army knife for a couple of different things.

I didn't spend much thoughts on all of this, please read it with a 
pinch of salt.


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