[Qgis-developer] featureAtId replacement

[Martin Dobias]

Hi Juergen

On Tue, Feb 12, 2013 at 10:26 AM, Jürgen E. <jef at norbit.de> wrote:
>>
>> I have been thinking also about providing convenience getFeatures()
>> call, for even shorter syntax:
>> layer.getFeatures( fid ).nextFeature(f)
>
> Creating the QgsFeatureRequest implicitly in getFeatures blocks the other
> options (restricting the attributes, no geometry...).
>
> I like the explicitness of the new interface.  No more "what was this
> true/false for again"?  Optionally adding those to getFeatures, would
> reintroduce that.

Yes, those are my concerns, too. At the same time, it would be good to
simplify API where it makes sense. I am aware of the fact that such
convenience functions would block using other options - but with
default options being "with geometry, with all attributes" people
typically should not need to use more options. Finally, I would be
opposing reintroduction of "true/false" arguments for getFeatures() as
those are really advanced options that "average" users should not need
to used (e.g. until recently OGR always fetched geometry and all
attributes).


> Maybe the current interface just takes a bit of getting use to?

Maybe, but IMHO we should provide simple API for simple cases to not
scare potential users :-)


> Having multiple constructors for QgsFeatureRequest (rect, fid, fids) however
> sounds acceptable ;)

Good :)

>> For a direct replacement of featureAtId() calls I have thought also
>> about adding getFeature() convenience call, that would return first
>> feature of a request:
>> f = layer.getFeature( fid )
>
> Why not keep featureAtId with the old interface on top of the new api then?
> And we still need to know if that feature actually exists...

featureAtId() accepts those true/false arguments which I consider
evil. Regarding existence of the feature, I guess checking f.isValid()
is sufficient?

Regards
Martin