c++ - 谷物多态序列化找不到序列化函数

Question

我目前正在尝试使用静态函数创建一个可序列化的基类，以序列化和反序列化派生类对象。我已阅读 Cereal Documentation for registering Polymorphic Relations 以及如何注册类型以及如何声明序列化函数。目标是像这样使用 Serializable ：

std::stringstream& ss Serializable::serialize(test);

我正在使用 Visual Studio 平台工具 2017(v141)。目标 Windows SDK 是 10.0.17134.0

但我无法构建我的应用程序并得到这 2 个错误 3 倍：

Error   C2338   cereal could not find any output serialization functions for the provided type and archive combination.

Error   C2338   cereal could not find any input serialization functions for the provided type and archive combination.

这是我的代码：

可序列化的.hpp

#pragma once
#include <string>
#include <cereal/archives/portable_binary.hpp>

class Serializable 
{
public:
Serializable() = default;
~Serializable() = default;
    virtual bool isAccessible() = 0;

    static std::stringstream serialize(std::shared_ptr<Serializable> serializable);
    static std::shared_ptr<Serializable> deserialize(std::stringstream& serialized);
};

可序列化的.cpp

#include "Serializable.hpp"

std::stringstream Serializable::serialize(std::shared_ptr<Serializable> serializable)
{
    std::stringstream ss;
    {
        cereal::PortableBinaryOutputArchive  ar(ss);
        ar << serializable;
    }
    return ss;
}

std::shared_ptr<Serializable> Serializable::deserialize(std::stringstream& serialized)
{
    cereal::PortableBinaryInputArchive ar(serialized);
    std::shared_ptr<Serializable> result = nullptr;
    ar >> result;
    return result;
}

测试对象.hpp

#pragma once
#include "Serializable.hpp"
#include <string>
#include <cereal/types/string.hpp>
#include <cereal/types/polymorphic.hpp>
#include <cereal/types/base_class.hpp>

class TestObject : public Serializable
{
public:
TestObject() = default;
TestObject(const std::string& name);
~TestObject() = default;
    std::string getName() const { return this->name; };



    template<class Archive>
    void serialize(Archive& ar)
    {
        ar(cereal::base_class<Serializable>(this), name);
    };

    virtual bool isAccessible() {
        return true;
    };

private:
    std::string name;
};

CEREAL_REGISTER_TYPE(TestObject)
CEREAL_REGISTER_POLYMORPHIC_RELATION(Serializable,TestObject)

测试对象.cpp

#include "TestObject.hpp"
TestObject::TestObject(const std::string& name)
    :TestObject(name){}

主文件

#include "TestObject.hpp"
#include "Serializable.hpp"
#include <memory>
#include <iostream>
#include <string>

int main(int argc, char **argv)
{
    std::shared_ptr<Serializable> test(new TestObject("Test"));
    auto ss = Serializable::serialize(test);
    std::shared_ptr<Serializable> deserialized = Serializable::deserialize(ss);
    auto test2 = dynamic_cast<TestObject*>(deserialized.get());
    std::cout << test2->getName();
    system("timeout 3");
    return 0;
}

这是完整的构建错误：

1>------ Build started: Project: SerializableTest, Configuration: Debug Win32 ------
1>TestObject.cpp
1>Serializable.cpp
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(462): error C2338: cereal could not find any output serialization functions for the provided type and archive combination.
1>
1> Types must either have a serialize function, load/save pair, or load_minimal/save_minimal pair (you may not mix these).
1> Serialize functions generally have the following signature:
1>
1> template<class Archive>
1>   void serialize(Archive & ar)
1>   {
1>     ar( member1, member2, member3 );
1>   }
1>
1>
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(347): note: see reference to function template instantiation 'ArchiveType &cereal::OutputArchive<ArchiveType,1>::processImpl<std::shared_ptr<Serializable>,0>(const T &)' being compiled
1>        with
1>        [
1>            ArchiveType=cereal::PortableBinaryOutputArchive,
1>            T=std::shared_ptr<Serializable>
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(347): note: see reference to function template instantiation 'ArchiveType &cereal::OutputArchive<ArchiveType,1>::processImpl<std::shared_ptr<Serializable>,0>(const T &)' being compiled
1>        with
1>        [
1>            ArchiveType=cereal::PortableBinaryOutputArchive,
1>            T=std::shared_ptr<Serializable>
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(290): note: see reference to function template instantiation 'void cereal::OutputArchive<cereal::PortableBinaryOutputArchive,1>::process<std::shared_ptr<Serializable>&>(T)' being compiled
1>        with
1>        [
1>            T=std::shared_ptr<Serializable> &
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(290): note: see reference to function template instantiation 'void cereal::OutputArchive<cereal::PortableBinaryOutputArchive,1>::process<std::shared_ptr<Serializable>&>(T)' being compiled
1>        with
1>        [
1>            T=std::shared_ptr<Serializable> &
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\serializable.cpp(8): note: see reference to function template instantiation 'ArchiveType &cereal::OutputArchive<ArchiveType,1>::operator <<<std::shared_ptr<Serializable>&>(T)' being compiled
1>        with
1>        [
1>            ArchiveType=cereal::PortableBinaryOutputArchive,
1>            T=std::shared_ptr<Serializable> &
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\serializable.cpp(8): note: see reference to function template instantiation 'ArchiveType &cereal::OutputArchive<ArchiveType,1>::operator <<<std::shared_ptr<Serializable>&>(T)' being compiled
1>        with
1>        [
1>            ArchiveType=cereal::PortableBinaryOutputArchive,
1>            T=std::shared_ptr<Serializable> &
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(851): error C2338: cereal could not find any input serialization functions for the provided type and archive combination.
1>
1> Types must either have a serialize function, load/save pair, or load_minimal/save_minimal pair (you may not mix these).
1> Serialize functions generally have the following signature:
1>
1> template<class Archive>
1>   void serialize(Archive & ar)
1>   {
1>     ar( member1, member2, member3 );
1>   }
1>
1>
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(730): note: see reference to function template instantiation 'ArchiveType &cereal::InputArchive<ArchiveType,1>::processImpl<std::shared_ptr<Serializable>,0>(const T &)' being compiled
1>        with
1>        [
1>            ArchiveType=cereal::PortableBinaryInputArchive,
1>            T=std::shared_ptr<Serializable>
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(730): note: see reference to function template instantiation 'ArchiveType &cereal::InputArchive<ArchiveType,1>::processImpl<std::shared_ptr<Serializable>,0>(const T &)' being compiled
1>        with
1>        [
1>            ArchiveType=cereal::PortableBinaryInputArchive,
1>            T=std::shared_ptr<Serializable>
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(660): note: see reference to function template instantiation 'void cereal::InputArchive<cereal::PortableBinaryInputArchive,1>::process<std::shared_ptr<Serializable>&>(T)' being compiled
1>        with
1>        [
1>            T=std::shared_ptr<Serializable> &
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\lib\cereal\include\cereal\cereal.hpp(660): note: see reference to function template instantiation 'void cereal::InputArchive<cereal::PortableBinaryInputArchive,1>::process<std::shared_ptr<Serializable>&>(T)' being compiled
1>        with
1>        [
1>            T=std::shared_ptr<Serializable> &
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\serializable.cpp(17): note: see reference to function template instantiation 'ArchiveType &cereal::InputArchive<ArchiveType,1>::operator >><std::shared_ptr<Serializable>&>(T)' being compiled
1>        with
1>        [
1>            ArchiveType=cereal::PortableBinaryInputArchive,
1>            T=std::shared_ptr<Serializable> &
1>        ]
1>k:\programme\c++\serializabletest\networkdebugs\serializabletest\serializable.cpp(17): note: see reference to function template instantiation 'ArchiveType &cereal::InputArchive<ArchiveType,1>::operator >><std::shared_ptr<Serializable>&>(T)' being compiled
1>        with
1>        [
1>            ArchiveType=cereal::PortableBinaryInputArchive,
1>            T=std::shared_ptr<Serializable> &
1>        ]
1>main.cpp
1>Generating Code...
1>Done building project "SerializableTest.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Answer 1

Afaik，如果你想调用cereal::base_class<Serializable>(this)，那么基类也需要一个serialize(Archive& ar)函数。由于没有理由在您的示例中序列化基类（没有成员变量），让我们简化TestObject serialize为ar(name);

那么你所缺少的只是 Serializable.cpp 中的一个#include <cereal/types/polymorphic.hpp>或者可能更好#include <cereal/types/memory.hpp>。如谷物 Docs-Polymorphism中所述，这包括允许PortableBinary[Input/Output]Archive查看CEREAL_REGISTER_POLYMORPHIC_RELATION您在衍生品中设置的内容。

例子：

可序列化的.hpp

#pragma once
#include <sstream>
#include <memory>

class Serializable
{
public:
    Serializable() = default;
    virtual ~Serializable() = default;
    virtual bool isAccessible() = 0;

    static std::stringstream serialize(const std::shared_ptr<Serializable>& serializable);
    static std::shared_ptr<Serializable> deserialize(std::stringstream& serialized);
};

可序列化的.cpp

#include "Serializable.hpp"
#include <cereal/archives/portable_binary.hpp>
#include <cereal/types/memory.hpp>

std::stringstream Serializable::serialize(const std::shared_ptr<Serializable>& serializable)
{
    std::stringstream ss;
    cereal::PortableBinaryOutputArchive ar(ss);
    ar(serializable);
    return ss;
}

std::shared_ptr<Serializable> Serializable::deserialize(std::stringstream& serialized)
{
    cereal::PortableBinaryInputArchive ar(serialized);
    std::shared_ptr<Serializable> result;
    ar(result);
    return result;
}

测试对象.hpp

#pragma once
#include "Serializable.hpp"
#include <string>
#include <cereal/types/polymorphic.hpp>

class TestObject : public Serializable
{
public:
    TestObject() = default;
    TestObject(const std::string& name) : name(name) {}
    ~TestObject() = default;
    std::string getName() const { return this->name; };

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

    bool isAccessible() override { return true; };
private:
    std::string name;
};

CEREAL_REGISTER_TYPE(TestObject);
CEREAL_REGISTER_POLYMORPHIC_RELATION(Serializable, TestObject)

主文件

#include "TestObject.hpp"
#include "Serializable.hpp"
#include <memory>
#include <sstream>
#include <iostream>

int main(int argc, char **argv)
{
    auto test = std::dynamic_pointer_cast<Serializable>(std::make_shared<TestObject>("Test"));
    auto ss = Serializable::serialize(test);
    auto deserialized = Serializable::deserialize(ss);
    auto test2 = std::dynamic_pointer_cast<TestObject>(deserialized);
    std::cout << test2->getName();

    return 0;
}

输出：

Test

Answer 2

由于您正在尝试序列化 ashared_ptr()您应该包括<cereal/types/memory.hpp>.