Re: [Boost-users] [serialization] empty xml output

Subject: Re: [Boost-users] [serialization] empty xml output
From: François Mauger (mauger_at_[hidden])
Date: 2011-03-27 07:08:46

Hi Olivier,

Your code looks ok.
On my system (Linux Ubuntu 9.10,gcc 4.4.1, Boost 1.44) I can check
that the following files 'parameters.hpp' and 'p1.cpp' compile, link and 
execute properly:
{{{
#ifndef PARAMETERS_HPP
#define PARAMETERS_HPP

//no need to include archives here:
#include <boost/serialization/nvp.hpp>

class rss_feeds_to_parse
{
public:

  bool all;
  template<class Archive> void serialize(Archive & ar, const unsigned 
int file_version)
  {
    ar & BOOST_SERIALIZATION_NVP(all);
  }
};

class parameters
{
public:
  rss_feeds_to_parse feeds;   
  template<class Archive> void serialize(Archive & ar, const unsigned 
int file_version)
  {
    ar & BOOST_SERIALIZATION_NVP(feeds);
  }
};

#endif // PARAMETERS_HPP
}}}
and
{{{
#include <fstream>
#include <assert.h>
#include <boost/archive/xml_oarchive.hpp> // archive is included here
#include <boost/serialization/nvp.hpp>

#include "parameters.hpp"

int main (void)
{
    parameters p;
    p.feeds.all = true;
    std::ofstream ofs ("test_parameters.xml");
    assert (ofs.good ());
    boost::archive::xml_oarchive oa (ofs);
    oa << BOOST_SERIALIZATION_NVP (p);
    return 0;
}
}}}

the output is:
{{{
shell> cat test_parameters.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<!DOCTYPE boost_serialization>
<boost_serialization signature="serialization::archive" version="7">
<p class_id="0" tracking_level="0" version="0">
    <feeds class_id="1" tracking_level="0" version="0">
        <all>1</all>
    </feeds>
</p>
</boost_serialization>
}}}
which is correct.

I suspect you have some other bits in your main that blanks the 
test_parameters.xml  file...

regards
frc
--
 >>> Olivier Tournaire a écrit :
> Hi all,
>
> I am trying to introduce XML serialization in my project, but even 
> with the simplest test, I cannot get something to work. Here is what I 
> did:
>
> #define PARAMETERS_HPP
> #include <boost/archive/xml_iarchive.hpp>
> #include <boost/archive/xml_oarchive.hpp>
> #include <iostream>
> class rss_feeds_to_parse
> {
> public:
>     bool all;
>     template<class Archive> void serialize(Archive & ar, const unsigned int file_version)
>     {
>         ar & BOOST_SERIALIZATION_NVP(all);
>     }
> };
> class parameters
> {
> public:
>     rss_feeds_to_parse feeds;
>     template<class Archive> void serialize(Archive & ar, const unsigned int file_version)
>     {
>         ar & BOOST_SERIALIZATION_NVP(feeds);
>     }
> };
> #endif // PARAMETERS_HPP
>
> Later, in my main, I have:
>
>     parameters p;
>     p.feeds.all = true;
>     std::ofstream ofs("test_parameters.xml");
>     assert(ofs.good());
>     boost::archive::xml_oarchive oa(ofs);
>     oa << BOOST_SERIALIZATION_NVP(p);
>
> It compiles, links and executes well, the file test_parameters.xml is 
> created ... but empty !
>
> What am I doing wrong?
>
> Hope you could help.
>
> Best regards,
>
> Olivier
> ------------------------------------------------------------------------
>
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-- 
François Mauger 
  Groupe "Interactions Fondamentales et Nature du Neutrino"
  NEMO-3/SuperNEMO Collaboration
LPC Caen-CNRS/IN2P3-UCBN-ENSICAEN
Département de Physique -- Université de Caen Basse-Normandie
Adresse/address:
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