Re: [Boost-users] [serialization] How to serialize an objectusingareference to its base class ?

From: Robert Ramey (ramey_at_[hidden])
Date: 2006-09-29 02:41:42

your saving as a pointer and loadign as a non pointer.

The following should work.

Robert Ramey

  "x y" <nosferatu_1_1_at_[hidden]> wrote in message news:20060929062027.89161.qmail_at_web31007.mail.mud.yahoo.com...

  #include <string>
  #include <sstream>
  #include <iostream>

  #include <boost/archive/xml_oarchive.hpp>
  #include <boost/archive/xml_iarchive.hpp>
  #include <boost/archive/binary_oarchive.hpp>
  #include <boost/archive/binary_iarchive.hpp>
  #include <boost/archive/text_oarchive.hpp>
  #include <boost/archive/text_iarchive.hpp>
  #include <boost/serialization/string.hpp>
  #include <boost/serialization/access.hpp>
  #include <boost/serialization/is_abstract.hpp>
  #include <boost/serialization/export.hpp>

  using namespace std;

  class base_class {
      friend class boost::serialization::access;

      public:
          base_class() : my_string("") { };
          base_class(string s) : my_string(s) { };
          virtual ~base_class() {};

          virtual void foo(void) = 0;

          template<class Archive>
          void serialize(Archive & ar, const unsigned int version)
          {
              ar & BOOST_SERIALIZATION_NVP(my_string);
          }

      public:
          string my_string;
  };

  BOOST_IS_ABSTRACT(base_class);
  BOOST_CLASS_EXPORT(base_class);

  class derived_class : public base_class {
      friend class boost::serialization::access;

      public:
          derived_class() : base_class(), my_int(0) {};
          derived_class(string s, int i) : base_class(s), my_int(i) {};
          virtual ~derived_class() {};

          void foo(void) {};

          template<class Archive>
          void serialize(Archive & ar, const unsigned int version)
          {
              ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(base_class)
                 & BOOST_SERIALIZATION_NVP(my_int);
          }

          int my_int;
  };

  BOOST_CLASS_EXPORT(derived_class);

  int main(int argc, char** argv) {
      try {
          stringstream ss;

          const derived_class d("aaa", 5);

          cout << "before: " << d.my_string << " " << d.my_int << endl;

          boost::archive::binary_oarchive oa(ss);
          oa << BOOST_SERIALIZATION_NVP(d);

          derived_class d2;
          boost::archive::binary_iarchive ia(ss);
          ia >> BOOST_SERIALIZATION_NVP(d2);
          cout << "after: " << d2.my_string << " " << d2.my_int << endl;
      }
      catch (const std::exception& ex) {
          cout << "std exception: " << ex.what() << endl;
      }
      catch (...) {
          cout << "unknown exception" << endl;        
      }

      return 0;
  }

  ----- Original Message ----
  From: Robert Ramey <ramey_at_[hidden]>
  To: boost-users_at_[hidden]
  Sent: Thursday, September 28, 2006 3:12:45 PM
  Subject: Re: [Boost-users] [serialization] How to serialize an object usingareference to its base class ?

  Without seeing your program I couldn't suggest much.

  Robert Ramey

  "x y" <nosferatu_1_1_at_[hidden]> wrote in message 
  news:20060928094242.89373.qmail_at_web31010.mail.mud.yahoo.com...
  It works now, but only with XML archives. When I serialize into a binary 
  archive I get a std::exception "bad alloc exception thrown".

  I forgot to mention that I'm working with Borland C++ Builder 6, boost 
  1_33_0

  I also tried with gcc 3.2.3 on linux with boost 1_33_1 and it also works 
  only with xml archives. With binary archive I get a "basic_string::resize" 
  exception.

  Robert Ramey <ramey_at_[hidden]> wrote:
  This works for pointers - not references. - the following - along with 
  compatible changes - should work.

  Robert Ramey

  void serialize(const base_class * src, std::ostream& dest) {
      boost::archive::binary_oarchive oa(dest);
      oa << BOOST_SERIALIZATION_NVP(src);
  }

  "x y" <nosferatu_1_1_at_[hidden]> wrote in message 
  news:20060927081505.10666.qmail_at_web31012.mail.mud.yahoo.com...
  Hi,

  I'm new to boost and I'm having some trouble serializing an object using a 
  reference to its base class.

  Although there are a lot of messages related to this topic in the newsgroups 
  and the doc, I did not find a workable answer to my proplem.

  In the following code, the function serialize takes a reference to 
  base_class as parameter. But the serialize method of derived_class is never 
  called.

  Did I miss something ?

  Thanks for your help
  Marc

  #include <string>
  #include <sstream>
  #include <iostream>

  #include <boost/archive/binary_oarchive.hpp>
  #include <boost/archive/binary_iarchive.hpp>
  #include <boost/serialization/string.hpp>
  #include <boost/serialization/access.hpp>
  #include <boost/serialization/is_abstract.hpp>
  #include <boost/serialization/export.hpp>

  using namespace std;

  class base_class {
      friend class boost::serialization::access;

      public:
          base_class() : my_string("") { };
          base_class(string s) : my_string(s) { };
          virtual ~base_class() {};

          virtual void foo(void) = 0;

          template<class Archive>
          void serialize(Archive & ar, const unsigned int version)
          {
              ar & BOOST_SERIALIZATION_NVP(my_string);
          }

      public:
          string my_string;
  };

  BOOST_IS_ABSTRACT(base_class);
  BOOST_CLASS_EXPORT(base_class);

  class derived_class : public base_class {
      friend class boost::serialization::access;

      public:
          derived_class() : base_class(), my_int(0) {};
          derived_class(string s, int i) : base_class(s), my_int(i) {};
          virtual ~derived_class() {};

          void foo(void) {};

          template<class Archive>
          void serialize(Archive & ar, const unsigned int version)
          {
              ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(base_class)
                 & BOOST_SERIALIZATION_NVP(my_int);
          }

          int my_int;
  };

  BOOST_CLASS_EXPORT(derived_class);

  void serialize(const base_class& src, std::ostream& dest) {
      boost::archive::binary_oarchive oa(dest);
      oa << BOOST_SERIALIZATION_NVP(src);
  }

  int main(int argc, char** argv) {
      try {
          std::stringstream ss;

          derived_class d("aaa", 5);
          cout << "before: " << d.my_string << " " << d.my_int << endl;
          serialize(d, ss);

          // deserialize
          derived_class d2;
          boost::archive::binary_iarchive ia(ss);
          ia >> d2;
          cout << "after: " << d2.my_string << " " << d2.my_int << endl;
      }
      catch (const std::exception& ex) {
          cout << "std exception: " << ex.what() << endl;     }
      catch (...) {
          cout << "unknown exception" << endl;
      }
  }

  Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls. Great rates 
  starting at 1¢/min.

  _______________________________________________
  Boost-users mailing list
  Boost-users_at_[hidden]
  http://lists.boost.org/mailman/listinfo.cgi/boost-users
  _______________________________________________
  Boost-users mailing list
  Boost-users_at_[hidden]
  http://lists.boost.org/mailman/listinfo.cgi/boost-users

  Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls. Great rates 
  starting at 1¢/min.

  _______________________________________________
  Boost-users mailing list
  Boost-users_at_[hidden]
  http://lists.boost.org/mailman/listinfo.cgi/boost-users 

  _______________________________________________
  Boost-users mailing list
  Boost-users_at_[hidden]
  http://lists.boost.org/mailman/listinfo.cgi/boost-users

------------------------------------------------------------------------------

  _______________________________________________
  Boost-users mailing list
  Boost-users_at_[hidden]
  http://lists.boost.org/mailman/listinfo.cgi/boost-users