[Boost-users] [serialization] [units] class_id and class_name to describe quantity dimension in serilization archive

Subject: [Boost-users] [serialization] [units] class_id and class_name to describe quantity dimension in serilization archive
From: alfC (alfredo.correa_at_[hidden])
Date: 2011-09-23 20:50:04

Hi, 
I am serializing a bunch of object that contains boost.units quantities. 
Boost.Units provides serialization for quantities already.
By default, the output file looks ok but I would like to add a class name to 
the object description.

Current, serializing quantity<si::length> q produces:

<q class_id="0" tracking_level="1" version="0" object_id="_0">
    <value>5</value>
</q>

Which doesn't give any information about the quantity at hand, not even for 
the human reading it. So, I tried to use BOOST_CLASS_EXPORT_GUID to register 
a name for the serialized class, but it is ignored.  Ideally I would like to 
have something like this, with a class_name description for example:

<q class_id="0" class_name = "quantity_si_length" tracking_level="1" 
version="0" object_id="_0">
    <value>5</value>
</q>

Is something like this possible? Below is the working code:

#include <fstream>
#include <boost/serialization/export.hpp>
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/units/systems/si/io.hpp>
using namespace boost::units;
BOOST_CLASS_EXPORT_GUID(quantity<si::length>, "quantity_si_length") 
//ignored

int main(int argc, char *argv[]) {
    std::ofstream ofs("filename.xml");
    boost::archive::xml_oarchive oa(ofs);

    quantity<si::length> q = 5.*si::meter;

    oa << BOOST_SERIALIZATION_NVP(q);

    return 0;
}