如何保存类的成员变量到其他类中

#include 

struct Point
{
    int x;
    int y;
};

struct MyStruct
{
    int a;
    int b;
    Point point;
};

template<typename T>
struct GetMemberClass{};

template<typename C, typename M>
struct GetMemberClass<M C::*>
{
    using ClassType = C;
    using MemberType = M;
};

template<typename MemberType>
bool is_member_object_pointer(MemberType entity)
{
    return std::is_member_object_pointer<MemberType>::value;
}

int main()
{
    MyStruct obj;
    MyStruct* ptr = &obj;
    obj.a = 5;
    obj.b = 7;
    obj.point.x = 11;
    obj.point.y = 12;

    obj.point = { 21, 22 };
    std::cout << obj.point.x << "," << obj.point.y << std::endl;

    auto TypePointX = &Point::x;

    std::cout << "std::is_member_object_pointer<"
        << typeid(TypePointX).name() << "> = "
        << std::is_member_object_pointer<decltype(TypePointX)>::value << std::endl;

    std::cout << "std::is_member_object_pointer<"
        << typeid(TypePointX).name() << "> = "
        << is_member_object_pointer(&Point::x) << std::endl;

    auto point = &MyStruct::point;
    ((obj.*point).*TypePointX) = 21;

    auto TypeA = &MyStruct::a;
    (obj.*TypeA) = 500;

    int MyStruct::*TypeAA = &MyStruct::a;

    std::cout << typeid(TypeA).name() << std::endl;
    std::cout << obj.*TypeA << std::endl;
    std::cout << obj.*TypeAA << std::endl;
    std::cout << ptr->*TypeA << std::endl;
    std::cout << "Hello World!\n";

    return 0;
}