Make small tutorial on output types and how to use them

[felixcremer]

I tried reproject today and got confused, that the result is a plain tuple when I input a NamedTuple.
I would have expected that the return type of reproject would be a NamedTuple in that case.

julia> using GeometryOps, GeoFormatTypes, Proj

julia> point = (X=11, Y=52)
(X = 11, Y = 52)

julia> reproject(point, source_crs=EPSG(4326), target_crs=EPSG(27704))
(4.949256544825357e6, 2.090589366405613e6)

[asinghvi17]

GeometryOps methods always output tuples points. But we could potentially special case named tuple points in rebuild? Or run a special convert for them?

I feel like that's pretty bad practice though. Is there a reason you need namedtuples out and can't use GI methods?

[felixcremer]

What do you mean by using GI methods?
GI doesn't have a reproject function.

I am trying to reproject a point that I am construction from a longitude latitude tuple and then continue working with it.

[asinghvi17]

I meant the GI accessors - GI.x, GI.y, etc

[asinghvi17]

Summarizing the discussion on Slack: GeometryOps has to choose a format to output in, we can't try to reconstruct everyone's geometries because that's costly and many geometry formats either can't be reconstructed (Shapefile), are extremely expensive to reconstruct (GEOS, GDAL, WellKnownGeometry) or don't support storing things like CRS (Shapefile, GeometryBasics).

We had experimented with rebuilding GeometryBasics geoms back to GeometryBasics in the past, it caused a lot of problems, so we decided to drop that and only rebuild using GeoInterface wrapper geoms backed by tuples and arrays of tuples.

In general GeometryOps outputs should only be accessed by GeoInterface methods. We should make that more clear and potentially have a small tutorial for that.

[asinghvi17]

Yeah that tutorial would be good! Maybe as a first thing

[asinghvi17]

@lazarusA are you going to be touching on this at all in your tutorial?