python/example/pickle1.cpp

/*
    This example shows how to make an Extension Class "pickleable".
    For more information refer to boost/libs/python/doc/pickle.html.
 */

#include <string>

#include <boost/python/class_builder.hpp>
namespace python = boost::python;

namespace { // Avoid cluttering the global namespace.

  // A friendly class.
  class world
  {
    private:
      std::string country;
      int secret_number;
    public:
      world(const std::string& country) : secret_number(0) {
        this->country = country;
      }
      std::string greet() const { return "Hello from " + country + "!"; }
      std::string get_country() const { return country; }
  };

  // Support for pickle.
  python::ref world_getinitargs(const world& w) {
      python::tuple result(1);
      result.set_item(0, w.get_country());
      return result.reference();
  }
}

BOOST_PYTHON_MODULE_INIT(pickle1)
{
  try
  {
    // Create an object representing this extension module.
    python::module_builder this_module("pickle1");

    // Create the Python type object for our extension class.
    python::class_builder<world> world_class(this_module, "world");

    // Add the __init__ function.
    world_class.def(python::constructor<std::string>());
    // Add a regular member function.
    world_class.def(&world::greet, "greet");

    // Support for pickle.
    world_class.def(world_getinitargs, "__getinitargs__");
  }
  catch(...)
  {
    python::handle_exception(); // Deal with the exception for Python
  }
}