RE: [Boost-users] Re: Boost.Serialization 1.32 trouble reading backanobject first serialized in an std::vector then by pointer

From: Yan Zhang (Yan.Zhang_at_[hidden])
Date: 2005-06-09 10:42:32

It strikes me that you can serialize the object and the address to it
and then deserialize the object and the address which now points to the
deserialized object. I used MFC serialization and I remembered that you
cannot do it. Do I misunderstand something here?

Yan

-----Original Message-----
From: boost-users-bounces_at_[hidden]
[mailto:boost-users-bounces_at_[hidden]] On Behalf Of Robert Ramey
Sent: Wednesday, June 08, 2005 8:51 PM
To: boost-users_at_[hidden]
Subject: [Boost-users] Re: Boost.Serialization 1.32 trouble reading
backanobject first serialized in an std::vector then by pointer

It just occured to me that this is an old problem which has now been
fixed
in the CVS. The problem occurs with version 1.32 when addresses of
objects
are stored in containers.  The problem occurs because objects are
deserialized to a temporary and then moved into the container.  This has
been addressed by adding the function reset_object_address calling it
during
the deserialzation.  This is explained in the CVS version.

Robert Ramey

Robert Ramey wrote:
> I'll look at this.  Give me a couple of days.
>
> Robert Ramey
>
> James Conrad wrote:
>> I'm evaluating the Boost.Serialization for use internal use as an
>> interchange format between a number of loose knit projects, and I've
>> run into a bit of trouble.
>>
>> I'm using Vc 7.1 in Visual Studio .NET 2003.
>>
>> It seems to me that, if I serialize an object first in an
>> std::vector, and then serialize it later by pointer, that there is
>> trouble reading it back.
>>
>> I boiled down the reproduction case to as little code as possible
>> below.
>>
>> When newPolygon (below) is loaded from the archive, I get a bogus
>> pointer for m_pLastVertex.  If I serialize using a binary archive, I
>> hit an assert in basic_iarchive.cpp line 371:
>>
>>         assert(new_cid == cid);
>>
>> Where cid is 576 and new_cid is 2.
>>
>> Any help with this would be appriciated,
>>
>> Thanks in advance,
>> -james conrad
>>
>>
>> #include <fstream>
>>
>> #define BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP
>>
>> #include <boost/archive/xml_oarchive.hpp>
>> #include <boost/archive/xml_iarchive.hpp>
>>
>> #include <boost/serialization/vector.hpp>
>> #include <boost/serialization/export.hpp>
>>
>> class Vector3
>> {
>> public:
>>     Vector3() {}
>>     Vector3( float x, float y, float z ) : _x(x), _y(y), _z(z) {}
>>
>>     friend class boost::serialization::access;
>>     template<class Archive>
>>     void serialize(Archive & ar, const unsigned int version)
>>     {
>>         ar & BOOST_SERIALIZATION_NVP(_x);
>>         ar & BOOST_SERIALIZATION_NVP(_y);
>>         ar & BOOST_SERIALIZATION_NVP(_z);
>>     }
>>
>>     float _x,_y,_z;
>> };
>>
>> BOOST_CLASS_EXPORT_GUID(Vector3, "Vector3")
>>
>> class Polygon
>> {
>> public:
>>     Polygon() : m_pLastVertex( NULL ) {}
>>
>>     friend class boost::serialization::access;
>>     template<class Archive>
>>     void serialize(Archive & ar, const unsigned int version)
>>     {
>>         ar & BOOST_SERIALIZATION_NVP(m_vertices);
>>         ar & BOOST_SERIALIZATION_NVP(m_pLastVertex);
>>     }
>>
>>     void addVertex( const Vector3& vert )
>>     {
>>         m_vertices.push_back( vert );
>>         m_pLastVertex = &m_vertices.back();
>>     }
>>
>>     std::vector<Vector3>    m_vertices;
>>     Vector3*                m_pLastVertex;
>> };
>>
>> BOOST_CLASS_EXPORT_GUID(Polygon, "Polygon")
>>
>> int main( int argc, char* argv[] )
>> {
>>     // create class instance
>>     Polygon poly;
>>     poly.addVertex( Vector3( 0.0f, 1.0f, 0.0f ) );
>>     poly.addVertex( Vector3( 1.0f, 0.12565f, 0.2f ) );
>>     poly.addVertex( Vector3( 15.0f, 1.22f, 6.7f ) );
>>     poly.addVertex( Vector3( 1.43f, 1.55f, 2.5f ) );
>>
>>     // create and open a character archive for output
>>     std::ofstream ofsx( "testout.xml" );
>>     boost::archive::xml_oarchive oax( ofsx );
>>
>>     // write class instance to archive
>>     oax << BOOST_SERIALIZATION_NVP(poly);
>>
>>     // close archive
>>     ofsx.close();
>>
>>     Polygon newPoly;
>>
>>     // create and open an archive for input
>>     std::ifstream ifs("testout.xml", std::ios::binary);
>>     boost::archive::xml_iarchive ia(ifs);
>>     // read class state from archive
>>     ia >> BOOST_SERIALIZATION_NVP( newPoly );
>>     // close archive
>>     ifs.close();
>>
>>     return 0;
>> }
>>
>>
>> Here is an example of the .xml output:
>>
>> <?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
>> <!DOCTYPE boost_serialization>
>> <boost_serialization signature="serialization::archive" version="3">
>> <poly class_id="0" tracking_level="1" version="0" object_id="_0">
>>     <m_vertices class_id="1" tracking_level="0" version="0">
>>         <count>4</count>
>>         <item class_id="2" tracking_level="1" version="0"
>>             object_id="_1"> <_x>0</_x>
>>             <_y>1</_y>
>>             <_z>0</_z>
>>         </item>
>>         <item object_id="_2">
>>             <_x>1</_x>
>>             <_y>0.12565</_y>
>>             <_z>0.2</_z>
>>         </item>
>>         <item object_id="_3">
>>             <_x>15</_x>
>>             <_y>1.22</_y>
>>             <_z>6.6999998</_z>
>>         </item>
>>         <item object_id="_4">
>>             <_x>1.4299999</_x>
>>             <_y>1.55</_y>
>>             <_z>2.5</_z>
>>         </item>
>>     </m_vertices>
>>     <m_pLastVertex class_id_reference="2"
>> object_id_reference="_4"></m_pLastVertex>
>> </poly>

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