Auto serialization#

Modules which have INCLUDE_MARSHAL in their vtk.module will opt their headers into the automated code generation of (de)serializers. Only classes which are annotated by the VTK_MARSHALAUTO wrapping hint will have generated serialization code.

Automated code generation#

The vtkWrapSerDes executable makes use of the WrappingTools package to automatically generate

  1. A serializer function with signature nlohmann:json Serialize_vtkClassName(vtkObjectBase*, vtkSerializer*)

  2. A deserializer function with signature void(const nlohmann::json&, vtkObjectBase*, vtkDeserializer*)

  3. A registrar function that registers

    • the serializer function with a serializer instance

    • the deserializer function with a deserializer instance

    • the constructor of the VTK class with a deserializer instance

    • It’s signature is int RegisterHandlers_vtkClassNameSerDes(void* ser, void* deser)

    • It more or less looks like:

      int RegisterHandlers_vtkObjectSerDes(void* ser, void* deser)
{
  int success = 0;
  if (auto* asObjectBase = static_cast<vtkObjectBase*>(ser))
  {
    if (auto* serializer = vtkSerializer::SafeDownCast(asObjectBase))
    {
      serializer->RegisterHandler(typeid(vtkObject), Serialize_vtkObject);
      success = 1;
    }
  }
  if (auto* asObjectBase = static_cast<vtkObjectBase*>(deser))
  {
    if (auto* deserializer = vtkDeserializer::SafeDownCast(asObjectBase))
    {
      deserializer->RegisterHandler(typeid(vtkObject), Deserialize_vtkObject);
      deserializer->RegisterConstructor("vtkObject", []() { return vtkObject::New(); });
      success = 1;
    }
  }
  return success;
}

Marshal hint macro#

  1. Classes which are annotated with VTK_MARSHALAUTO are considered by the vtkWrapSerDes executable.

  2. Classes annotated with VTK_MARSHALMANUAL are hand coded in the same module. Here are some examples:

    • Common/Core/vtkCollectionSerDesHelper.cxx for Common/Core/vtkCollection.h

    • Common/DataModel/vtkCellArraySerDesHelper.cxx for Common/DataModel/vtkCellArray.h

Convenient script to annotate headers and module#