dirty_hacks.h

// adapted from http://bloglitb.blogspot.de/2011/12/access-to-private-members-safer.html

namespace Rob {
template<typename Tag, typename Tag::type M>
struct Rob {
  friend typename Tag::type get(Tag) {
    return M;
  }
};
} // namespace Rob

#define CREATE_ACCESS_TAG(unique_id, class_name, member_name, member_type) \
namespace Rob {                                                            \
struct unique_id {                                                         \
  using member_type_ = member_type;                                        \
  using type = member_type_ class_name::*;                                 \
  friend type get(unique_id);                                              \
};                                                                         \
template struct Rob<unique_id, &class_name::member_name>;                  \
} // namespace Rob

#define ACCESS(unique_id, object) ((object).*get(Rob::unique_id()))