[QGIS-Developer] Using memory layer in Processing with SAGA and GRASS

[matteo]

Hi Nyall,

> No - neither SAGA nor GRASS have any concept of QGIS memory layers.
> You need to give them a disk-based file path to save their outputs to.

ok, clear now why this was not working


> If you use a memory layer as an input to these algs it will also have
> to save it out to a disk based format, but this is done automatically
> by saving to a file in the temp folder. We could potentially do the
> same thing to allow SAGA/GRASS algs to output to a memory layer by
> first saving the output to a shp in the temp folder, then loading that
> file and copying the features to a memory layer. But it would be
> rather inefficient and counter productive - you're still being forced
> to loop over the disk-based format, so you're just adding extra
> processing for little gain.

so within a script (or a Processing plugin) both input layer and output
one have to come from a disk saved file.

Thanks for the explanation!

Cheers

Matteo