如何通过指向基类的指针序列化派生类？ Derived::serialize 未调用

Question

我正在尝试通过使用指向基类的指针增强序列化来使派生类可序列化。

Base::serialization 调用。未调用 Derived::serialization。

我做错了什么？

#include <sstream>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/serialization/serialization.hpp>
#include <boost/serialization/assume_abstract.hpp>

struct Base
{
    int x;
    Base() { x = 0; }
    virtual ~Base() {}

    template<class Archive>
    void serialize(Archive &ar, const unsigned int version)
    {
        ar & x;
    }
};

BOOST_SERIALIZATION_ASSUME_ABSTRACT(Base)

struct Derived : Base
{
    int y;
    Derived() { x = 1; y = 2; }
    virtual ~Derived() {}

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

int main()
{
    Derived derived;
    Base *basePtr = &derived;

    std::string s;
    std::stringstream ss(s);
    boost::archive::binary_oarchive oa(ss);

    oa << *basePtr;
}

Answer 1

首先，你不是通过指针序列化，修复它：

oa << basePtr;

其次，需要注册派生类型：

oa.register_type<Derived>();

或者，在序列化函数内部：

ar.template register_type<Derived>();

您可能_还想查看注册类信息以进行序列化：http://www.boost.org/doc/libs/1_57_0/libs/serialization/doc/special.html#export

---

更新到评论/编辑问题：

您的问题代码序列化 Base* 并反序列化 Derived。类型不相关，这永远行不通。它们必须相同。

另外，注册读取输入存档的 Derived 类型。

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#include <sstream>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/serialization/serialization.hpp>
#include <boost/serialization/assume_abstract.hpp>

struct Derived;

struct Base
{
    int x;
    Base() { x = 0; }
    virtual ~Base() {}

    template<class Archive>
    void serialize(Archive &ar, const unsigned int version)
    {
        ar.template register_type<Derived>();
        ar & x;
    }
};

BOOST_SERIALIZATION_ASSUME_ABSTRACT(Base)

struct Derived : Base
{
    int y;
    Derived() { x = 1; y = 2; }
    virtual ~Derived() {}

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

int main()
{
    std::stringstream ss;

    {
        Derived derived;
        Base *basePtr = &derived;

        boost::archive::binary_oarchive oa(ss);
        oa.register_type<Derived>();

        oa << basePtr;
        ss.flush();
    }

    {
        boost::archive::binary_iarchive ia(ss);
        ia.register_type<Derived>();

        Base *basePtr = nullptr;

        ia >> basePtr;
        std::cout << "basePtr->x = " << basePtr->x << "\n";
        if (Derived* derivedPtr = dynamic_cast<Derived*>(basePtr))
            std::cout << "derivedPtr->y = " << derivedPtr->y << "\n";
    }
}