Re: [Boost-users] Boost Serialize and derived classes

Subject: Re: [Boost-users] Boost Serialize and derived classes
From: John Yamokoski (yamokosk_at_[hidden])
Date: 2008-09-16 18:24:14

Yea I have done that. I have read the sections on exporting several
times and thought my example was implementing this feature correctly.
Yet every time I run it, the code only spits out the base class. The
only complete example from the documentation shows the explicit
declaration of derived class names. Once again, here is my test code:

main.cpp:

class base
{
        friend class boost::serialization::access;
        template<class Archive>
        void serialize(Archive & ar, const unsigned int file_version)
        {
                ar & BOOST_SERIALIZATION_NVP(dval);
        }
public:
        base() : dval(0.0) {}
        base(double b) : dval(b) {}
        double dval;
};

class derived : public base
{
        friend class boost::serialization::access;
        template<class Archive>
        void serialize(Archive & ar, const unsigned int file_version)
        {
                boost::serialization::void_cast_register<derived,
base>(static_cast<derived *>(NULL),static_cast<base *>(NULL));
                ar & BOOST_SERIALIZATION_NVP(ival);
        }
public:
        derived() : base(0.0), ival(0) {}
        derived(int a, double b) : base(b), ival(a) {}
        int ival;
};

BOOST_CLASS_EXPORT_GUID(derived, "derived");

class manager
{
        friend class boost::serialization::access;
        template<class Archive>
        void serialize(Archive & ar, const unsigned int file_version) {
                ar & BOOST_SERIALIZATION_NVP(objs);
        }
public:
        std::list<base*> objs;
};

void SerializeTest::testSerialize()
{
        manager mgr;

        // Creat some data to save
        derived *d1, *d2;
        d1 = new derived(1, 1.0);
        d2 = new derived(2, 3.0);

        mgr.objs.push_back( d1 );
        mgr.objs.push_back( d2 );

        {
                std::ofstream ofs("out.xml");
                assert(ofs.good());
                boost::archive::xml_oarchive oa(ofs);
                oa << BOOST_SERIALIZATION_NVP(mgr);
                ofs.close();
        }

        manager new_mgr;

        {
                std::ifstream ifs("out.xml");
                assert(ifs.good());
                boost::archive::xml_iarchive ia(ifs);
                ia >> BOOST_SERIALIZATION_NVP(new_mgr);
                ifs.close();
        }

        {
                std::ofstream ofs("check.xml");
                assert(ofs.good());
                boost::archive::xml_oarchive oa(ofs);
                oa << BOOST_SERIALIZATION_NVP(new_mgr);
                ofs.close();
        }

        delete d1, d2;
}

And here is the output of out.xml:

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<!DOCTYPE boost_serialization>
<boost_serialization signature="serialization::archive" version="4">
<mgr class_id="0" tracking_level="0" version="0">
        <objs class_id="1" tracking_level="0" version="0">
                <count>2</count>
                <item_version>0</item_version>
                <item class_id="2" tracking_level="1" version="0"
object_id="_0">
                        <dval>1</dval>
                </item>
                <item class_id_reference="2" object_id="_1">
                        <dval>3</dval>
                </item>
        </objs>
</mgr>

On Tue, Sep 16, 2008 at 6:32 PM, Robert Ramey <ramey_at_[hidden]> wrote:
> Look in the documentation of "export" and BOOST_CLASS_EXPORT

-- 
J.D. Yamokoski
Department of Mechanical & Aerospace Engineering
University of Florida
MAE-A Room 331
Gainesville, FL 32611
e-mail: yamokosk_at_[hidden]
fax: [phone]