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

From: Robert Ramey (ramey_at_[hidden])
Date: 2006-09-27 13:57:41

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;        
      }
  }

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