Question

I am looking for some design advices for the following problem:

I am using boost geometry, I have a couple of custom geometry types compatible with boost geometry (via traits), but most of the types I am using are typedefs.

class MyPoint
{
  // custom stuff
};
// declare traits for MyPoint for use wih boost geometry here

class MyTaggedPoint : public MyPoint
{
  // more custom stuff
};
// declare traits for MyTaggedPoint for use wih boost geometry here

// example typedefs
typedef boost::geometry::model::polygon<MyPoint>        Polygon;
typedef boost::geometry::model::polygon<MyTaggedPoint>  TaggedPolygon;

My problem is when I want to serialize/deserialize my geometries.

Let’s say all geometries are stored in a binary field in a database. If I would have a base geometry class, I would probably just write g->type() (4 bytes) and call g->save(some_outputstream) and write all of that to the binary field. Then when reading the binary field I would simply read the bytes and cast to appropriate geometry type.

But Boost geometries do not have a common base class.

How do you guys usually approach serialization when there are multiple types that can be stored as binary and you do not have a shared base class ?

I was thinking of maybe having a Serializer class, that returns a boost.Any and then the geometry can be casted afterward with the type that would be stored in the (de)serializer? But then the serializer would need a save method for each geometry types ? ex: Save(myPolygon), Save(myPoint)

Any ideas/experiences?

Answer 1

Boost’s serialization supports non-invasive serialization if you do not wish to reimplement the wheel. You may even be able to find library support for their geometry types somewhere. The interface is somewhat complicated due to XML concerns unfortunately.