怎样用boost::serialization去序列化派生模板类

本篇是boost::serialization 用基类指针转存派生类（错误多多，一波三折）的姊妹篇，这里只不过做一个总结。

先来看一个基类

class base_class
{
public:
base_class(int m=0) : base_member_(0) {}
virtual ~base_class() {}

virtual void print_data() = 0;
protected:
int base_member_;
//other member...
};

它的一个模板派生类

template<typename T>
class divided_class : public base_class
{
public:
divided_class(int m = 0, T d = T()) : base_class(m), diveded_member_(d) {}
virtual ~divided_class() {}

protected:
T diveded_member_;
//other member....
};

现在我们来看怎样用boost::serialization来序列化模板类

1.首先我们用一个宏来告诉boost base_class是一个抽象类：

BOOST_SERIALIZATION_ASSUME_ABSTRACT(base_class);

2.分别在基类和派生了中定义序列化函数

基类的序列化函数：

private:
class boost::serialization::access;
template<typename Archive>
void serialize(Archive & ar, const unsigned int file_version)
{
ar & BOOST_SERIALIZATION_NVP(base_member_);
//ar & BOOST_SERIALIZATION_NVP(other member...);
}

这个序列化函数为什么是私有的，请自己看boost文档

模板派生类的序列化函数为：

private:
class boost::serialization::access;
template<typename Archive>
void serialize(Archive & ar, const unsigned int file_version)
{
ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(base_class);//这个地方直接用ar & boost::serialization::base_object<base_class>(*this)会出错
ar & BOOST_SERIALIZATION_NVP(diveded_member_);
//ar & BOOST_SERIALIZATION_NVP(other member...);
}

3.在save中注册派生模板类

void save()
{
std::ofstream ofs("t8.xml");
boost::archive::xml_oarchive oa(ofs);

base_class* int_base = new divided_class<int>(1, 3);
base_class* str_base = new divided_class<std::string>(1, "wyp");
base_class* float_base = new divided_class<float>(1, 3.1415926f);

//Now the tricky point is to register class in serialize
oa.template register_type<divided_class<int>>(NULL);
oa.template register_type<divided_class<std::string>>(NULL);
oa.template register_type<divided_class<float>>(NULL);

//begin serialize
oa & BOOST_SERIALIZATION_NVP(int_base);
oa & BOOST_SERIALIZATION_NVP(str_base);
oa & BOOST_SERIALIZATION_NVP(float_base);
}

4.在load中同样也要注册派生模板类，而且要和save中注册的一样

void load()
{
std::ifstream ifs("t8.xml");
boost::archive::xml_iarchive ia(ifs);

base_class* int_base;
base_class* str_base;
base_class* float_base;

//Now the tricky point is to register class in serialize
ia.template register_type<divided_class<int>>(NULL);
ia.template register_type<divided_class<std::string>>(NULL);
ia.template register_type<divided_class<float>>(NULL);

//begin serialize
ia & BOOST_SERIALIZATION_NVP(int_base);
ia & BOOST_SERIALIZATION_NVP(str_base);
ia & BOOST_SERIALIZATION_NVP(float_base);

//do something...
int_base->print_data();std::cout << std::endl;
str_base->print_data();std::cout << std::endl;
float_base->print_data();std::cout << std::endl;
}

基本上就这几步！！！！