谷类:序列化多态类型

Question

我遇到了序列化多态类型的问题。实际上，我只是将示例拆分到：http://uscilab.github.io/cereal/polymorphism.html中的几个文件中。它编译得很好，但在运行时我得到一个异常，告诉我我不能序列化一个多态类型，当到达代码中的这一行时，它没有注册: oarchive( ptr1，ptr2 )；它应该将ptr1和ptr2的内容序列化为一个流。

我附加了这些文件，这样任何人都可以看到发生了什么。

提前感谢您的宝贵时间！最好，罗杰。

////////////// IBaseClass.h
    #ifndef _IBASECLASS_H_
    #define _IBASECLASS_H_

    // A pure virtual base class
    class IBaseClass
    {
    public:
      virtual void sayType() = 0;
    };

    #endif

    ////////////// DerivedClass.h
    #ifndef DERIVEDCLASS_H_
    #define DERIVEDCLASS_H_

    #include "IBaseClass.h"

    #include <cereal/types/polymorphic.hpp>

    class DerivedClass : public IBaseClass {
        void sayType();

        int x;

        template<class Archive>
        void serialize( Archive & ar )
        { ar( x ); }
    };

    #include <cereal/archives/binary.hpp>
    #include <cereal/archives/xml.hpp>
    #include <cereal/archives/json.hpp>

    // Register DerivedClassOne
    CEREAL_REGISTER_TYPE(DerivedClass);

    #endif /* DERIVEDCLASS_H_ */

    ////////////// DerivedClass2.h
    #ifndef DERIVEDCLASS2_H_
    #define DERIVEDCLASS2_H_

    #include "IBaseClass.h"

    #include <cereal/types/polymorphic.hpp>

    class DerivedClass2 : public IBaseClass {
        void sayType();

        float y;

        template<class Archive>
        void serialize( Archive & ar )
        { ar( y ); }
    };

    #include <cereal/archives/binary.hpp>
    #include <cereal/archives/xml.hpp>
    #include <cereal/archives/json.hpp>

    CEREAL_REGISTER_TYPE(DerivedClass2);

    ////////////// main.cpp
    #include "DerivedClass.h"
    #include "DerivedClass2.h"
    #include <iostream>
    #include <fstream>
    #include <memory>

    #include <cereal/archives/xml.hpp>
    #include <cereal/types/polymorphic.hpp>

    int main(int argc, char* argv[])
    {
        {
            std::ofstream os( "polymorphism_test.xml" );
            cereal::XMLOutputArchive oarchive( os );

            // Create instances of the derived classes, but only keep base class pointers
            std::shared_ptr<IBaseClass> ptr1 = std::make_shared<DerivedClass>();
            std::shared_ptr<IBaseClass> ptr2 = std::make_shared<DerivedClass2>();
            oarchive( ptr1, ptr2 );
          }

          {
            std::ifstream is( "polymorphism_test.xml" );
            cereal::XMLInputArchive iarchive( is );

            // De-serialize the data as base class pointers, and watch as they are
            // re-instantiated as derived classes
            std::shared_ptr<IBaseClass> ptr1;
            std::shared_ptr<IBaseClass> ptr2;
            iarchive( ptr1, ptr2 );

            // Ta-da! This should output:
            ptr1->sayType();  // "DerivedClassOne"
            ptr2->sayType();  // "EmbarrassingDerivedClass. Wait.. I mean DerivedClassTwo!"
          }

          return 0;
    }

Answer 1

https://uscilab.github.io/cereal/polymorphism.html

因为您没有在cereal：：base_class上进行任何序列化(这)，所以没有从您的派生类到基类的路径。尝试添加：

CEREAL_REGISTER_POLYMORPHIC_RELATION(BaseClass，DerivedClassOne) CEREAL_REGISTER_POLYMORPHIC_RELATION(BaseClass，EmbarrassingDerivedClass)