can_query_free.cpp
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//
// cpp03/can_query_free.cpp
// ~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "asio/query.hpp"
#include <cassert>
struct prop
{
};
struct object
{
friend int query(const object&, prop) { return 123; }
};
namespace asio {
template<>
struct is_applicable_property<object, prop>
{
static const bool value = true;
};
namespace traits {
template<>
struct query_free<object, prop>
{
static const bool is_valid = true;
static const bool is_noexcept = true;
typedef int result_type;
};
} // namespace traits
} // namespace asio
int main()
{
assert((asio::can_query<object, prop>::value));
assert((asio::can_query<const object, prop>::value));
}