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[/
/ Copyright (c) 2003-2025 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)
/]
[section:ResolveToken Resolve token requirements]
A resolve token is a [link boost_asio.overview.model.completion_tokens completion
token] for completion signature `void(error_code,
ip::basic_resolver_results<InternetProtocol>)`, for a specified
`InternetProtocol`.
[heading Examples]
A free function as a resolve token:
void resolve_handler(
const boost::system::error_code& ec,
boost::asio::ip::tcp::resolver::results_type results)
{
...
}
A resolve token function object:
struct resolve_handler
{
...
void operator()(
const boost::system::error_code& ec,
boost::asio::ip::tcp::resolver::results_type results)
{
...
}
...
};
A lambda as a resolve token:
resolver.async_resolve(...,
[](const boost::system::error_code& ec,
boost::asio::ip::tcp::resolver::results_type results)
{
...
});
A non-static class member function adapted to a resolve token using
`std::bind()`:
void my_class::resolve_handler(
const boost::system::error_code& ec,
boost::asio::ip::tcp::resolver::results_type results)
{
...
}
...
resolver.async_resolve(...,
std::bind(&my_class::resolve_handler,
this, std::placeholders::_1,
std::placeholders::_2));
A non-static class member function adapted to a resolve token using
`boost::bind()`:
void my_class::resolve_handler(
const boost::system::error_code& ec,
boost::asio::ip::tcp::resolver::results_type results)
{
...
}
...
resolver.async_resolve(...,
boost::bind(&my_class::resolve_handler,
this, boost::asio::placeholders::error,
boost::asio::placeholders::results));
Using [link boost_asio.reference.use_future use_future] as a resolve token:
std::future<boost::asio::ip::tcp::resolver::results_type> f =
resolver.async_resolve(..., boost::asio::use_future);
...
try
{
boost::asio::ip::tcp::resolver::results_type r = f.get();
...
}
catch (const system_error& e)
{
...
}
Using [link boost_asio.reference.use_awaitable use_awaitable] as a resolve token:
boost::asio::awaitable<void> my_coroutine()
{
try
{
...
boost::asio::ip::tcp::resolver::results_type r =
co_await resolver.async_resolve(
..., boost::asio::use_awaitable);
...
}
catch (const system_error& e)
{
...
}
}
[endsect]
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