Question

boost::asio::ip::tcp::socket& socket() const is returning _socket which is of type boost::asio::ip::tcp::socket is giving me this error

error: invalid initialization of non-const reference of type ‘boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >&’ from a temporary of type ‘const boost::reference_wrapper<const boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> > >’

socket() function is only getter and is not altering the state of this object so why does it fire error if I make it const ?

Answer 1

Because the function is returning a reference to an object. When the const member function is called, the returned reference must also be const.

boost::asio::ip::tcp::socket const& socket() const

However, depending on what you want to do with that socket reference, you might have to return a non-const reference, in which case another option is to declare the getter function as non-const or declare the socket mutable in the class definition

mutable boost::asio::ip::tcp::socket socket_