[gdal-dev] Call for discussion on RFC 59 (v2): GDAL/OGR utilities as a library

[Even Rouault]

Hi Homme,

>  From my point of view anything that makes the new API feel less like a
> wrapper
> around a system call is great: passing expensive objects like datasets and
> enabling progress functions is important.  Hopefully this would also mean
> passing objects as cutline layers for gdalwarp and also clipsrc for ogr2ogr
> (including geometry objects for the latter?).

Yes, https://lists.osgeo.org/pipermail/gdal-dev/2015-September/042512.html

"""
- a few setters can be added, for example, to set a progress function. Or 
possibly auxiliary objects,  like the cutline layer for gdalwarp.
"""

> 
> The idea of an option structure parsed from an array of strings sounds
> nice and
> easy to work with.  Is the option structure intended to be created for
> each call
> to an utility, or is it envisaged it can hang around and be reused (and
> modified)? 

Hopefully it should be reusable. It means that we must be careful not to 
modify it during a particular execution of the utility.

> I.e. will the API include the ability to retrieve options
> already
> set in the option structure, and set specific options?

I'm not sure about getters. The idea would also be to minimize the number of 
setters to just what is not possible through strings.
The idea being that when the utility syntax is extended, for example something 
that was a particular case is made more generic, we don't necessarily want to 
give too much visibility on the field members of the option structure (as 
raised in https://lists.osgeo.org/pipermail/gdal-dev/2015-August/042472.html )

> If so how will
> options
> that can be set multiple times like `gdal_translate -b` be set at the C
> level
> (i.e. what would your python example of `options = gdal.TranslateOptions();
> options.bands = [ 1, 2, 3 ]` look like in C)?

char* argv[] = { "-b", "1", "-b", "2", "-b", "3", NULL };
GDALTranslateOptionsParse* psOptions = GDALTranslateOptionsNew(argv);

Even

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