ceph/src/boost/libs/asio/doc/requirements/ReadHandler.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:ReadHandler Read handler requirements]
   9
  10 A read handler must meet the requirements for a [link
  11 boost_asio.reference.Handler handler]. A value `h` of a read handler class
  12 should work correctly in the expression `h(ec, s)`, where `ec` is an lvalue of
  13 type `const error_code` and `s` is an lvalue of type `const size_t`.
  14
  15 [heading Examples]
  16
  17 A free function as a read handler:
  18
  19   void read_handler(
  20       const boost::system::error_code& ec,
  21       std::size_t bytes_transferred)
  22   {
  23     ...
  24   }
  25
  26 A read handler function object:
  27
  28   struct read_handler
  29   {
  30     ...
  31     void operator()(
  32         const boost::system::error_code& ec,
  33         std::size_t bytes_transferred)
  34     {
  35       ...
  36     }
  37     ...
  38   };
  39
  40 A non-static class member function adapted to a read handler using `bind()`:
  41
  42   void my_class::read_handler(
  43       const boost::system::error_code& ec,
  44       std::size_t bytes_transferred)
  45   {
  46     ...
  47   }
  48   ...
  49   socket.async_read(...,
  50       boost::bind(&my_class::read_handler,
  51         this, boost::asio::placeholders::error,
  52         boost::asio::placeholders::bytes_transferred));
  53
  54 [endsect]