Mesh Inheritance

Here is the inheritance diagram for various APF-related mesh interfaces:

apf::Mesh is a type representing an interface to a read-only mesh, and apf::Mesh2 inherits from it and adds functionality to modify the mesh. The vast majority of code operates on apf::Mesh and apf::Mesh2 objects, and as a result is portable across different underlying representations (MDS or Simmetrix). There are a few functions that only work if the apf::Mesh2 object is known, for example, to be actually an apf::MeshMDS object, but despite this we never let the user actually see the type apf::MeshMDS, it is always accessed as an apf::Mesh2, which is also a valid apf::Mesh.