boost中的load_construct_data：放置新問題

Question

我嘗試在boost的幫助下使用非默認構造函數序列化派生指針類。

在編譯我得到一個錯誤：

Derived.h: In function ‘void boost::serialization::load_construct_data(Archive&, const A::Derived*, unsigned int)’: 

in Derived.h: error: no matching function for call to ‘operator new(long unsigned int, const A::Derived*&) 

我包括<new>到Derived.h，但我有一種感覺，我忘了做一些事情。 這是我對代碼的粗略估計。

我有虛函數和非默認的構造（在Base.h）

#include <boost/archive/text_oarchive.hpp> 
#include <boost/archive/text_iarchive.hpp> 
#include <boost/serialization/export.hpp> 
namespace A{ 

    class Base 

    { 

    public: 

      int getID(){return ID}; 

      //non default constructor 
      Base(param1, param2, param3):ID(param1+param2), BaseFlag(param3) {}; 
      Base(param1, param3):ID(param1), BaseFlag(param3) {}; 

      //some virtual functions 
      virtual void Foo1(); 
      virtual void Foo2(); 
      ... 

    private: 

      int ID; 
      bool BaseFlag; 
      ... 

      //void serialize function 
      friend class boost::serialization::access; 
      template<class Archive> 
      void serialize(Archive & ar, const unsigned int version) 
      { 

      } 

    }; 

} 
//end of namespace A 
//implementation is in another file - exporting key 
BOOST_CLASS_EXPORT_KEY(Base) 

有一個派生類（在Derived.h）

#include <boost/serialization/base_object.hpp> 
#include <boost/archive/text_oarchive.hpp> 
#include <boost/archive/text_iarchive.hpp> 
#include <boost/serialization/export.hpp> 
#include <new> 
#include "Base.h" 

namespace A{ 

    //derived class 
    class Derived: public Base 
    { 
    public: 
     //non default constructor 
     Derived(param3):Base(param3, false); 
     ... 
    private: 
     friend class boost::serialization::access; 
     template<class Archive> 

     // serialize base class information 
     void serialize(Archive & ar, const unsigned int version) 
     { 
      ar & boost::serialization::base_object<Base>(*this); 
     } 

     //prototype of save_construct_data for non-default constructor 
     template<class Archive> friend 
      void boost::serialization::save_construct_data(Archive & ar, 
         const Derived * t, const unsigned int file_version); 

     //prototype of load_construct_data for non-default constructor 
     template<class Archive> friend 
      void boost::serialization::load_construct_data(Archive & ar, 
         const Derived * t, const unsigned int file_version); 
    }; 
} 
//end of namespace A 

//export derived class 
BOOST_CLASS_EXPORT_KEY(Derived) 

//describe save_construct_data 
namespace boost { 
    namespace serialization { 
     template<class Archive> 
     inline void save_construct_data(Archive & ar, const A::Derived * t, const unsigned int file_version) 
     { 
      // save data required to construct instance 
      ar << t->ID; 

     } 

     template<class Archive> 
     inline void load_construct_data(Archive & ar, const A::Derived * t, const unsigned int file_version) 
     { 
      int ID; 
      // load data required to construct instance 
      ar >> ID; 
      ::new(t) A::Derived(ID); 

     } 


    } 
} 

而且某處的基礎類在main.cpp中，我想保存並加載派生類。所以，我在開頭提到的編譯錯誤使我無法繼續。

任何提示我缺少什麼？

Answer 1

我相信編譯器會抱怨，因爲您正在嘗試構建標記爲const的內存中的Derived。在此聲明：

template<class Archive> friend 
    void boost::serialization::load_construct_data(Archive & ar, 
       const Derived * t, const unsigned int file_version); 

我想你想Derived *t，不const Derived *t。

的boost docs也沒有const在函數簽名：

template<class Archive> 
inline void load_construct_data(
    Archive & ar, my_class * t, const unsigned int file_version 
){ 
    // retrieve data from archive required to construct new instance 
    int attribute; 
    ar >> attribute; 
    // invoke inplace constructor to initialize instance of my_class 
    ::new(t)my_class(attribute); 
}