# persistence/persistent_callback.hpp

    #ifndef STLPLUS_PERSISTENT_CALLBACK
    #define STLPLUS_PERSISTENT_CALLBACK
    ////////////////////////////////////////////////////////////////////////////////

    //   Author:    Andy Rushton
    //   Copyright: (c) Southampton University 1999-2004
    //              (c) Andy Rushton           2004 onwards
    //   License:   BSD License, see ../docs/license.html

    //   Persistence for pointers to polymorphic classes using the callback approach.

    //   This works on a set of classes. Each subclass has a set of callback
    //   (non-method) functions that enable create/dump/restore operations. Each
    //   subclass must be registered with the persistence dump/restore context so
    //   that the system knows how to handle it.

    //   This approach is suited to classes that cannot be modified to add
    //   persistence methods. See persistent_interface for a more C++-like way of
    //   handling polymorphism.

    //   Objects are always dumped/restored as pointers to the superclass T.

    //   Multiple pointers to the same object are handled in the same way as for
    //   simple pointers

    //   Only classes registered with the context can be dumped and restored as
    //   polymorphic types - see dump_context::register_callback and
    //   restore_context::register_callback. Attempting to use any unrecognised class
    //   will throw an exception.

    ////////////////////////////////////////////////////////////////////////////////

    #include "persistence_fixes.hpp"
    #include "persistent_contexts.hpp"

    ////////////////////////////////////////////////////////////////////////////////

    namespace stlplus
    {

      // exceptions: persistent_dump_failed
      template<typename T>
      void dump_callback(dump_context&, const T* const data);

      // exceptions: persistent_restore_failed
      template<typename T>
      void restore_callback(restore_context&, T*& data);

    } // end namespace stlplus

      ////////////////////////////////////////////////////////////////////////////////
    #include "persistent_callback.tpp"
    #endif