c：如何在构造函数中初始化std :: pair的成员

typedef std::pair<boost::asio::ip::tcp::socket,boost::asio::ip::tcp::socket>  socket_pair;

class ConnectionPair {
private:
    socket_pair _sockPair;
public:
    ConnectionPair(boost::asio::io_service &ios);
}

如何在构造函数中初始化对中的套接字？以下内容无法编译：

ConnectionPair::ConnectionPair(asio::io_service &ios):
    _ios(ios),_sockPair(asio::ip::tcp::socket(ios),asio::ip::tcp::socket(ios)){
}

编辑：这是编译器错误.请享用：

/boost_1_47_0/boost/asio/basic_io_object.hpp: In copy constructor ‘boost::asio::basic_socket<boost::asio::ip::tcp,boost::asio::stream_socket_service<boost::asio::ip::tcp> >::basic_socket(const boost::asio::basic_socket<boost::asio::ip::tcp,boost::asio::stream_socket_service<boost::asio::ip::tcp> >&)’:

/boost_1_47_0/boost/asio/basic_socket.hpp:43:1:   instantiated from ‘std::pair<_T1,_T2>::pair(const _T1&,const _T2&) [with _T1 = boost::asio::basic_stream_socket<boost::asio::ip::tcp>,_T2 = boost::asio::basic_stream_socket<boost::asio::ip::tcp>]’
/devel/msm1/connection.cpp:8:67:   instantiated from here
/boost_1_47_0/boost/asio/basic_io_object.hpp:163:3: error: ‘boost::asio::basic_io_object<IoObjectService>::basic_io_object(const boost::asio::basic_io_object<IoObjectService>&) [with IoObjectService = boost::asio::stream_socket_service<boost::asio::ip::tcp>,boost::asio::basic_io_object<IoObjectService> = boost::asio::basic_io_object<boost::asio::stream_socket_service<boost::asio::ip::tcp> >]’ is private
/boost_1_47_0/boost/asio/basic_socket.hpp:43:1: error: within this context
In file included from /boost_1_47_0/boost/asio.hpp:30:0,