ceph/src/boost/libs/asio/doc/requirements/ResolveHandler.qbk

   1 [/
   2  / Copyright (c) 2003-2016 Christopher M. Kohlhoff (chris at kohlhoff dot com)
   3  /
   4  / Distributed under the Boost Software License, Version 1.0. (See accompanying
   5  / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6  /]
   7
   8 [section:ResolveHandler Resolve handler requirements]
   9
  10 A resolve handler must meet the requirements for a [link
  11 boost_asio.reference.Handler handler]. A value `h` of a resolve handler
  12 class should work correctly in the expression `h(ec, i)`, where `ec` is an
  13 lvalue of type `const error_code` and `i` is an lvalue of type `const
  14 ip::basic_resolver_iterator<InternetProtocol>`. `InternetProtocol` is the
  15 template parameter of the [link boost_asio.reference.ip__resolver_service
  16 `resolver_service`] which is used to initiate the asynchronous operation.
  17
  18 [heading Examples]
  19
  20 A free function as a resolve handler:
  21
  22   void resolve_handler(
  23       const boost::system::error_code& ec,
  24       boost::asio::ip::tcp::resolver::iterator iterator)
  25   {
  26     ...
  27   }
  28
  29 A resolve handler function object:
  30
  31   struct resolve_handler
  32   {
  33     ...
  34     void operator()(
  35         const boost::system::error_code& ec,
  36         boost::asio::ip::tcp::resolver::iterator iterator)
  37     {
  38       ...
  39     }
  40     ...
  41   };
  42
  43 A non-static class member function adapted to a resolve handler using `bind()`:
  44
  45   void my_class::resolve_handler(
  46       const boost::system::error_code& ec,
  47       boost::asio::ip::tcp::resolver::iterator iterator)
  48   {
  49     ...
  50   }
  51   ...
  52   resolver.async_resolve(...,
  53       boost::bind(&my_class::resolve_handler,
  54         this, boost::asio::placeholders::error,
  55         boost::asio::placeholders::iterator));
  56
  57 [endsect]