auto_ptr, string serialization

27 Apr 2006

      I have a class that inherit from another, both implement serialization

the derived class has this code:

#ifndef _GENREMETADATA_H_
#define _GENREMETADATA_H_

#include "fetchableMetadataObject.h"

#include <boost/serialization/split_member.hpp>
#include <boost/serialization/string.hpp>

class GenreMetadata : public FetchableMetadataObject
{
public:
	.....

private:
     std::string m_abbreviation;
     std::string m_displayName;
     std::string m_name;

     std::auto_ptr<std::vector<GenreMetadata> > m_childGenresMetadata;
     std::auto_ptr<std::vector<GenreMetadata> > m_parentGenresMetadata;
     std::auto_ptr<std::string> m_description;
     std::auto_ptr<GenreMetadata> m_primaryParentGenreMetadata;

     template<class Archive> void serialize(Archive & inArchive,  
const unsigned int version)
     {
         //serialize the base class
         //
         inArchive & BOOST_SERIALIZATION_BASE_OBJECT_NVP 
(FetchableMetadataObject);

         //then our own properties
         //
         inArchive & BOOST_SERIALIZATION_NVP(m_abbreviation);
         inArchive & BOOST_SERIALIZATION_NVP(m_displayName);
         inArchive & BOOST_SERIALIZATION_NVP(m_name);
         inArchive & BOOST_SERIALIZATION_NVP(m_childGenresMetadata);
         inArchive & BOOST_SERIALIZATION_NVP(m_parentGenresMetadata);
         inArchive & BOOST_SERIALIZATION_NVP(m_description);
         inArchive & BOOST_SERIALIZATION_NVP 
(m_primaryParentGenreMetadata);
     }

};
#endif //_GENREMETADATA_H_

i included a version of auto_ptr serialization:
#include <list>
#include <memory>
#include <fstream>

#include <boost/config.hpp> // std::autoptr inteface wrong in dinkumware
#include <boost/detail/workaround.hpp>

#include <boost/archive/xml_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/detail/workaround.hpp>

#include <boost/serialization/split_free.hpp>

namespace boost {
     namespace serialization {

         /////////////////////////////////////////////////////////////
         // implement serialization for auto_ptr<T>
         // note: this must be added to the boost namespace in order to
         // be called by the library
         template<class Archive, class T>
         inline void save(
                          Archive & ar,
                          const std::auto_ptr<T> &t,
                          const unsigned int file_version
                          ){
             // only the raw pointer has to be saved
             // the ref count is rebuilt automatically on load
             T *objectPtr = t.get();
             ar << BOOST_SERIALIZATION_NVP(objectPtr);
         }

         template<class Archive, class T>
         inline void load(
                          Archive & ar,
                          std::auto_ptr<T> &t,
                          const unsigned int file_version
                          ){
             T *objectPtr;
             ar >> BOOST_SERIALIZATION_NVP(objectPtr);
             // note that the reset automagically maintains the  
reference count
#if BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, == 1)
             t.release();
             t = std::auto_ptr<T>(objectPtr);
#else
             t.reset(objectPtr);
#endif
         }

         // split non-intrusive serialization function member into  
separate
         // non intrusive save/load member functions
         template<class Archive, class T>
         inline void serialize(
                               Archive & ar,
                               std::auto_ptr<T> &t,
                               const unsigned int file_version
                               ){
             split_free(ar, t, file_version);
         }

     } // namespace serialization
} // namespace boost

When i compile this code i get the following error:
../../common_rn/import/boost/debug/include/boost-1_33_1/boost/ 
serialization/access.hpp:109: error: 'struct std::basic_string<char,  
std::char_traits<char>, std::allocator<char> >' has no member named  
'serialize'

I looked at the serialization code for string and it treats it as a  
primitive type. Could my problem come from there. Notice how it  
complains about the string contained  in the auto_ptr, but not the  
other strings. Also it does not complain about the array contain in  
the auto_ptr.

Also if i split the serialization of my object an manually try to  
archive the string object, it complain about the serialization if i  
pass in a pointer to the string, but not if i pass the object itself

any help appreciated
Best,
Olivier Destrebecq
olivierd@real.com

Olivier Destrebecq

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