#include <cstdio>
#include <msgpack.hpp>
#include <boost/describe/class.hpp>
template <
 bool as_map,
 class Stream,
 class T,
 class D1 = boost::describe::describe_members<T, boost::describe::mod_any_access>
>
void msgpack_pack(msgpack::packer<Stream>& packer, const T& obj, std::integral_constant<bool, as_map>)
{
 if constexpr (as_map)
 {
 packer.pack_map(boost::mp11::mp_size<D1>::value);
 boost::mp11::mp_for_each<D1>([&](auto D) {
 packer.pack(D.name);
 packer.pack(obj.*D.pointer);
 });
 }
 else
 {
 packer.pack_array(boost::mp11::mp_size<D1>::value);
 boost::mp11::mp_for_each<D1>([&](auto D) {
 packer.pack(obj.*D.pointer);
 });
 }
}
template <
 bool as_map,
 class Stream,
 class T,
 class D1 = boost::describe::describe_members<T, boost::describe::mod_any_access>
>
void msgpack_pack(Stream& stream, const T& obj, std::integral_constant<bool, as_map> option)
{
 msgpack::packer<Stream> packer(&stream);
 msgpack_pack(packer, obj, option);
}
struct example_struct
{
 std::string msg;
 std::vector<float> v; 
};
BOOST_DESCRIBE_STRUCT(example_struct, (), (msg, v))
int main()
{
 example_struct data;
 data.msg = "Hello there!";
 data.v.resize(10);
 msgpack::sbuffer buf1, buf2;
 msgpack_pack(buf1, data, std::true_type{}); // as map
 msgpack_pack(buf2, data, std::false_type{}); // as array
 
 printf("Serialized as map %zu - serialized as array %zu\n", buf1.size(), buf2.size());
 return 0;
}