Boost C++ Libraries

An iterator connect handler must meet the requirements for a handler. A value h of an iterator connect 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 the type Iterator used in the corresponding connect() or async_connect()` function.

Examples

A free function as an iterator connect handler:

void connect_handler(
    const boost::system::error_code& ec,
    boost::asio::ip::tcp::resolver::iterator iterator)
{
  ...
}

An iterator connect handler function object:

struct connect_handler
{
  ...
  template <typename Iterator>
  void operator()(
      const boost::system::error_code& ec,
      Iterator iterator)
  {
    ...
  }
  ...
};

A lambda as an iterator connect handler:

boost::asio::async_connect(...,
    [](const boost::system::error_code& ec,
      boost::asio::ip::tcp::resolver::iterator iterator)
    {
      ...
    });

A non-static class member function adapted to an iterator connect handler using std::bind():

void my_class::connect_handler(
    const boost::system::error_code& ec,
    boost::asio::ip::tcp::resolver::iterator iterator)
{
  ...
}
...
boost::asio::async_connect(...,
    std::bind(&my_class::connect_handler,
      this, std::placeholders::_1,
      std::placeholders::_2));

A non-static class member function adapted to an iterator connect handler using boost::bind():

void my_class::connect_handler(
    const boost::system::error_code& ec,
    boost::asio::ip::tcp::resolver::iterator iterator)
{
  ...
}
...
boost::asio::async_connect(...,
    boost::bind(&my_class::connect_handler,
      this, boost::asio::placeholders::error,
      boost::asio::placeholders::iterator));