get_class_meta_in_one_line

cxx11_get_meta.cpp

#define MAKE_PAIR(text) std::pair<std::string, decltype(text)>{#text, text}
template<typename T>
constexpr static inline auto apply(T const & args)
{
    return args;
}

template<typename T, typename T1, typename... Args>
constexpr static inline auto apply(T const & t, const T1& first, const Args&... args)
{
    return apply(std::tuple_cat(t, std::make_tuple(MAKE_PAIR(first))), args...);
}

#define META(...) auto meta(){ return apply(std::tuple<>(), __VA_ARGS__); }

struct person
{
    std::string name;
    int age;
    META(name, age) //定义一个支持变参的meta函数
};
int main()
{
    person p = {“tom”, 20};
    auto tp = p.meta();
    static_assert(std::is_same(std::tuple<std::pair<std::string, int>>, decltype(tp), “not same”);
    //tp在内存中是这样的 {{“name”:”tom”}, {“age”:20}};
    return 0;
}