1 //
2 // cpp03/can_prefer_unsupported.cpp
3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6 //
7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9 //
10
11 #include <boost/asio/prefer.hpp>
12 #include <cassert>
13
14 template <int>
15 struct prop
16 {
17 static const bool is_preferable = true;
18 };
19
20 template <int>
21 struct object
22 {
23 };
24
25 namespace boost {
26 namespace asio {
27
28 template<int N, int M>
29 struct is_applicable_property<object<N>, prop<M> >
30 {
31 static const bool value = true;
32 };
33
34 } // namespace asio
35 } // namespace boost
36
main()37 int main()
38 {
39 assert((boost::asio::can_prefer<object<1>, prop<2> >::value));
40 assert((boost::asio::can_prefer<object<1>, prop<2>, prop<3> >::value));
41 assert((boost::asio::can_prefer<object<1>, prop<2>, prop<3>, prop<4> >::value));
42 assert((boost::asio::can_prefer<const object<1>, prop<2> >::value));
43 assert((boost::asio::can_prefer<const object<1>, prop<2>, prop<3> >::value));
44 assert((boost::asio::can_prefer<const object<1>, prop<2>, prop<3>, prop<4> >::value));
45 }
46