12345678910111213141516171819202122232425262728293031 |
- // Copyright Louis Dionne 2013-2017
- // Distributed under the Boost Software License, Version 1.0.
- // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
- #include <boost/hana/assert.hpp>
- #include <boost/hana/not.hpp>
- #include <boost/hana/type.hpp>
- #include <string>
- #include <vector>
- namespace hana = boost::hana;
- int main() {
- // Checking for a member
- struct Person { std::string name; };
- auto has_name = hana::is_valid([](auto&& p) -> decltype((void)p.name) { });
- Person joe{"Joe"};
- static_assert(has_name(joe), "");
- static_assert(!has_name(1), "");
- // Checking for a nested type
- auto has_value_type = hana::is_valid([](auto t) -> hana::type<
- typename decltype(t)::type::value_type
- > { });
- static_assert(has_value_type(hana::type_c<std::vector<int>>), "");
- static_assert(!has_value_type(hana::type_c<Person>), "");
- }
|