How can I use it like this：const char* name = hana::get_name(&my_struct::name);

[segeter]

struct my_struct { BOOST_HANA_DEFINE_STRUCT(my_struct, (std::string, name) ); }; int main() { const char* name = hana::get_name(&my_struct::name); }

Thanks

[ricejasonf]

It appears you are trying to get the name of a Struct member from its pointer-to-member.

With the provided macros such as BOOST_HANA_DEFINE_STRUCT this is not supported. You would have to go dive into the implementation details to make such a function.

One option is to bypass the macro and implement hana::accessors_impl yourself so you can make a function that reliably does what you want here.

I made an example based on hana::struct_detail which holds info about the member pointer. This is not officially supported so use at your own risk.

#include <boost/callable_traits.hpp>
#include <boost/hana.hpp>
#include <string>

namespace hana = boost::hana;
namespace callable_traits = boost::callable_traits;

struct my_struct {
    BOOST_HANA_DEFINE_STRUCT(my_struct, (std::string, name) );
};

template <typename T, typename M, M memptr>
struct match_memptr_t : std::false_type { };

template <typename Name, typename M, M memptr>
struct match_memptr_t<hana::pair<Name,
        hana::struct_detail::member_ptr<M, memptr>>, M, memptr>
    : std::true_type
{ };

template <auto memptr>
constexpr auto match_memptr = [](auto X) {
    return match_memptr_t<decltype(X), decltype(memptr), memptr>();
};

template <auto memptr>
constexpr auto get_name() {
    using Struct = callable_traits::class_of_t<decltype(memptr)>;
    auto result = hana::find_if(hana::accessors<Struct>(),
                                match_memptr<memptr>).value();
    return hana::first(result);
}

int main() {
    static_assert(get_name<&my_struct::name>() == BOOST_HANA_STRING("name"));
    char const* name = get_name<&my_struct::name>().c_str();
}

https://godbolt.org/z/Kvfdor45z

Note that you can't get static information from a function parameter's value so you have to pass it as a template parameter. Also, I used C++17 deduced auto non-type-template-parameter. Without it the interface would be more verbose.