How to tag some types to build a type list from th

问题:

I generated some types with an external tool. I include some of them depending on the application. I tried to play with both boost preprocessor and boost mpl to tag my generated types and build an mpl vector of these tagged types. Unfortunately, my trick only works when I am including the headers I need in a single file with my TypeRegistry.

// TypeRegistry.h
typedef ::boost::mpl::vector<> TypeRegistryRegisteredTypes0;

# define TYPE_REGISTRY_REGISTER_TYPE(T)            \
  typedef ::boost::mpl::push_back<                 \
      BOOST_PP_CAT(                                \
          TypeRegistryRegisteredTypes,             \
          BOOST_PP_COUNTER                         \
      ),                                           \
      ##T                                          \
  >::type                                          \
  BOOST_PP_CAT(TypeRegistryRegisteredTypes, BOOST_PP_ADD(BOOST_PP_COUNTER,1))

# define TYPE_REGISTRY_SYNC_REGISTERED_TYPES()     \
  typedef BOOST_PP_CAT(                            \
      TypeRegistryRegisteredTypes,                 \
      BOOST_PP_COUNTER                             \
      ) TypeRegistryRegisteredTypes

template
<
    class RegisteredTypesBase,
    class RegisteredTypesVector
>
class TypeRegistry { ... };

This is the macro I use to register a type.

// A.h
class A : public IBase { ... };
TYPE_REGISTRY_REGISTER_TYPE(A);
#include BOOST_PP_UPDATE_COUNTER()

Here we are, in a source file, say main.h:

#include "TypeRegistry.h"
#include "A.h"
#include "B.h"
#include "C.h"
...
TYPE_REGISTRY_SYNC_REGISTERED_TYPES();
TypeRegistry< IBase, TypeRegistryRegisteredTypes > typeRegistry;
auto a = typeRegistry.instanceFromName("A");
auto b = typeRegistry.instanceFromName("B");
auto c = typeRegistry.instanceFromName("C");

As I said, the trick only works because I am including all my interesting types --so to say-- at the same time. How would you perform an automatic type recording without having to include them all in a single file (that is, compiling a source file which is including its header file should be sufficient)?