...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
A resolve handler must meet the requirements for a handler.
A value h
of a resolve handler
class should work correctly in the expression h(ec,
i)
,
where ec
is an lvalue of
type const error_code
and i
is an lvalue of type
const ip::basic_resolver_iterator<InternetProtocol>
. InternetProtocol
is the template parameter of the resolver_service
which is used to
initiate the asynchronous operation.
A free function as a resolve handler:
void resolve_handler( const boost::system::error_code& ec, boost::asio::ip::tcp::resolver::iterator iterator) { ... }
A resolve handler function object:
struct resolve_handler { ... void operator()( const boost::system::error_code& ec, boost::asio::ip::tcp::resolver::iterator iterator) { ... } ... };
A non-static class member function adapted to a resolve handler using bind()
:
void my_class::resolve_handler( const boost::system::error_code& ec, boost::asio::ip::tcp::resolver::iterator iterator) { ... } ... resolver.async_resolve(..., boost::bind(&my_class::resolve_handler, this, boost::asio::placeholders::error, boost::asio::placeholders::iterator));