Re: [Boost-users] [serialization] std::shared_ptr with Boost >= 1.53

4 May 2015

      Dear Robert,

see below for a simple test program that illustrates what I'm trying to
do. This compiles with Boost 1.58, but fails on 1.53 with the error message

/opt/boost153/include/boost/serialization/access.hpp:118:11: error: no
member
      named 'serialize' in 'std::__1::shared_ptr<test>'
        t.serialize(ar, file_version);

I need to support Boost versions starting with 1.53. Thus I have two
options:

- do serialization of std::shared_ptr myself
- include the 1.58 boost/serialization/shared_ptr.hpp for older
Boost-versions.

What is the best way ?

Thanks and Best Regards,
Beet

/*******************************************************/
// Compile with
// g++ --std=c++11 -o sharedptr sharedptr.cpp -I /opt/boost158/include/
// -L/opt/boost158/lib -lboost_serialization -lboost_system
// on MacOS, Linux

#include <iostream>
#include <memory>
#include <sstream>

#include <boost/archive/xml_oarchive.hpp>
#include <boost/archive/xml_iarchive.hpp>
#include <boost/serialization/nvp.hpp>
#include <boost/serialization/vector.hpp>
#include <boost/serialization/shared_ptr.hpp>

class test {
	///////////////////////////////////////////////////////////////////////
	friend class boost::serialization::access;

	template<typename Archive>
	void serialize(Archive & ar, const unsigned int) {
		using boost::serialization::make_nvp;
		ar
		& BOOST_SERIALIZATION_NVP(secret_);
	}
	///////////////////////////////////////////////////////////////////////

public:
	test(): secret_(1) {}

private:
	int secret_;
};

int main() {
  std::vector<std::shared_ptr<test> > t_vec, t_vec2;
  std::ostringstream oss;

  t_vec.push_back(std::shared_ptr<test>(new test()));

  // save data to archive
  {
    boost::archive::xml_oarchive oa(oss);
    // write class instance to archive
    oa & BOOST_SERIALIZATION_NVP(t_vec);
    // archive and stream closed when destructors are called
    // Data is now in oss
  }

  // load data from archive
  {
    std::istringstream iss(oss.str());
    boost::archive::xml_iarchive ia(iss);
    // read class state from archive
    ia & BOOST_SERIALIZATION_NVP(t_vec2);
    // archive and stream closed when destructors are called
  }

  return 0;
}

/*******************************************************/

Am 04.05.15 um 01:34 schrieb Robert Ramey:
...
beet-2 wrote
...
Dear Robert,
thanks a lot! Do I understand it correctly, that I could easily create
my own serializer for std::shared_ptr by just (de)serializing the
contained "raw" pointer and wrapping it into a std::shared_ptr in the
case of de-serialization ?
No. You have to keep track of other shared pointers point
I had assumed from the question that the situation was something like:
// version 1
myclass {
    boost::shared_ptr m_p
...
}
// version 2
myclass {
    std::shared_ptr m_p
    ...
};
and the question was asking how the latest version code would de-serialize
older version (version 1) archives (data files)
Robert Ramey
--
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