cereal_LoadAndConstruct(3)

template<class T>

struct cereal::LoadAndConstruct< T >"A class that allows cereal to load smart pointers to types that have no default constructor.

If your class does not have a default constructor, cereal will not be able to load any smart pointers to it unless you overload LoadAndConstruct for your class, and provide an appropriate load_and_construct method. You can also choose to define a member static function instead of specializing this class.

The specialization of LoadAndConstruct must be placed within the cereal namespace:

struct MyType
{


  MyType( int x ); // note: no default ctor


  int myX;


  // Define a serialize or load/save pair as you normally would


  template <class Archive>


  void serialize( Archive & ar )


  {


    ar( myX );


  }
};
// Provide a specialization for LoadAndConstruct for your type
namespace cereal
{


  template <> struct LoadAndConstruct<MyType>


  {


    // load_and_construct will be passed the archive that you will be loading


    // from as well as a construct object which you can use as if it were the


    // constructor for your type.  cereal will handle all memory management for you.


    template <class Archive>


    static void load_and_construct( Archive & ar, cereal::construct<MyType> & construct )


    {


      int x;


      ar( x );


      construct( x );


    }


    // if you require versioning, simply add a const std::uint32_t as the final parameter, e.g.:


    // load_and_construct( Archive & ar, cereal::construct<MyType> & construct, std::uint32_t const version )


  };
} // end namespace cereal

Please note that just as in using external serialization functions, you cannot get access to non-public members of your class by befriending cereal::access. If you have the ability to modify the class you wish to serialize, it is recommended that you use member serialize functions and a static member load_and_construct function.

load_and_construct functions, regardless of whether they are static members of your class or whether you create one in the LoadAndConstruct specialization, have the following signature:

// generally Archive will be templated, but it can be specific if desired
template <class Archive>
static void load_and_construct( Archive & ar, cereal::construct<MyType> & construct );
// with an optional last parameter specifying the version: const std::uint32_t version

Versioning behaves the same way as it does for standard serialization functions.

Template Parameters