Re: [Boost-users] xml serialization : compilation fails

From: Hughes, James (jhughes_at_[hidden])
Date: 2007-05-04 10:15:44

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] 
> [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Cyril
> Sent: 04 May 2007 15:02
> To: boost-users_at_[hidden]
> Subject: [Boost-users] xml serialization : compilation fails
> 
> Hello all,
> I have a problem while attempting to serialize a simple 
> object using xml (text works fine !).
> 
> This is my code :
> 
> // SomeData.h
> #include <boost/serialization/utility.hpp> #include 
> <boost/serialization/base_object.hpp>
> 
> class OBJECTS_API InternalData {
> public:
>     InternalData();
>     virtual ~InternalData();
>     virtual int getInternals() const = 0;
> private:
>     friend class boost::serialization::access;
>     template<class Archive>
>     void serialize(Archive & ar, const unsigned int version)
>     {
>     }
> };
> 
> class OBJECTS_API RealData : public InternalData {
> public:
>     RealData(int internals=0);
>     int getInternals() const;
> private:
>     int _internals;
> 
>     friend class boost::serialization::access;
>     template<class Archive>
>     void serialize(Archive & ar, const unsigned int version)
>     {
>         ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(InternalData)
>            & BOOST_SERIALIZATION_NVP(_internals);
>     }
> };
> 
> class OBJECTS_API SomeData {
> public:
>     SomeData(int internals=0);
>     ~SomeData();
>     InternalData* getInternals() const;
> private:
>     InternalData* _data;
>     static InternalData* createData(int internals);
> 
>     friend class boost::serialization::access;
>     template<class Archive>
>     void serialize(Archive & ar, const unsigned int version)
>     {
>         //ar.register_type(static_cast<RealData*>(0));
>         ar & BOOST_SERIALIZATION_NVP(_data);
>     }
> };
> //////////////////
> // somewhere else
> const SomeData data(4);
> boost::archive::xml_oarchive xoa(archive); //archive is a 
> file stream xoa << data;
> 
> ////////////////////
> 
> This fails to compile because :
> // basic_xml_oarchive.hpp
> // Anything not an attribute and not a name-value pair is an 
> // error and should be trapped here.
> template<class T>
> void save_override(T & t, BOOST_PFTO int) {
>         // If your program fails to compile here, its most 
> likely due to
>         // not specifying an nvp wrapper around the variable to
>         // be serialized.
>         BOOST_STATIC_ASSERT(0 == sizeof(T)); }
> 
> I can't see why my code isn't correct according to that 
> constraint. Any help ?
> 
> Thanks in advance.

I just had a very similar (if not the same) problem - I spent some time
assigning GUID's to all the classes, and ensuring all base classes were
correctly serialised using BOOST_SERIALIZATION_BASE_OBJECT_NVP and that
seems to have fixed the problem. Whether it was that or something else
that got changed during the figuring out period is anyones guess!!

See BOOST_CLASS_EXPORT_GUID

James

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