Indexes can not work with negative values

[ObiWahn]

The problem becomes visible if the use_nodecache.py example is run with an osm file that contains nodes with negative ints.

» ./use_nodecache.py map_minimal.osm cache
Traceback (most recent call last):
  File "/osmgj/./use_nodecache.py", line 31, in <module>
    osmium.apply(reader, lh, WayHandler(idx))
  File "/osmgj/./use_nodecache.py", line 17, in way
    locations.append(idx.get(n.ref))  # note that cache is used here
                     ^^^^^^^^^^^^^^
TypeError: get(): incompatible function arguments. The following argument types are supported:
    1. (self: osmium.index.LocationTable, id: int) -> osmium.osm._osm.Location

Invoked with: <osmium.index.LocationTable object at 0x7f675e724170>, -138468

When using a fix positive nonexistent id like 100 a KeyError is raised.

To me it looks like the problem is here. The osmium lib uses unsigned integers and even ensures this with enable_if.

    using LocationTable =
        osmium::index::map::Map<osmium::unsigned_object_id_type, osmium::Location>;
    using IndexFactory =
        osmium::index::MapFactory<osmium::unsigned_object_id_type, osmium::Location>;

    py::class_<LocationTable>(m, "LocationTable")
        .def("set", &LocationTable::set, py::arg("id"), py::arg("loc"))
        .def("get", &LocationTable::get, py::arg("id"))

      # Set up the OSM handler
        node_cache = UnsingedLocationTableWrapper(osmium.index.create_map('flex_mem'))
        handler_create_json = OSMHandler(node_cache)
>       handler_read_node_cache = osmium.NodeLocationsForWays(node_cache)
E       TypeError: __init__(): incompatible constructor arguments. The following argument types are supported:
E           1. osmium._osmium.NodeLocationsForWays(arg0: osmium::index::map::Map<unsigned long, osmium::Location>)
E
E       Invoked with: <osmgj.UnsingedLocationTableWrapper object at 0x7f2586e1da90>

I have tried to use a python wrapper, but at some points the c/c++ structs are expected and my wrapping code is not accepted.

As Python only knows about ints and has not notion of unsigned and the osmium lib requires unsigned this library should do a conversion && check if the value is in the rage or raise a ValueError (too big/small).

Or offer some other mechanic to allow the usage of negative integers.

[lonvia]

This works as expected an is documented here. The error message could be better but that is out of control of pyosmium. We are using the automated value checks of pybind11 here.