boost::asio usage in self-contained class - c++

Question

Trying to get my head around the boost classes. What I want to do, differs from the boost asio tutorial in that, the tutorial has a main() where the io_service object is instantiated. That is then passed to the class implementing asio via its constructor.
What I want to do, is to eliminate the instantiation of io_service in the main and have the implementing class be "self-contained" in that, it will declare its own io_service and socket. I must be reading the example with tunnel-vision, because I cannot figure out how to drop the instantiation of io_service into my socket class.
At first, I was getting "error C2758: 'xxx::io_service' : must be initialized in constructor base/member initializer list". So, I thought I'd do that and added "io_service(new boost::asio::io_service()), socket(io_service)" to the class initializer list. That gave me "error C2354: 'xxx::io_service' : initialization of reference member requires a temporary variable", which, after some googling, made sense.
So, my question is, how can I adjust the tutorial code to eliminate the main()?

Answer 1

Is this what you're after:
Move the io_service into the class (not by reference). And all usages as well.
I opted to put the join into the destructor.
#include <cstdlib>
#include <deque>
#include <iostream>
#include <boost/bind.hpp>
#include <boost/asio.hpp>
#include <boost/thread/thread.hpp>
#include "chat_message.hpp"
using boost::asio::ip::tcp;
typedef std::deque<chat_message> chat_message_queue;
class chat_client
{
public:
chat_client(std::string host, std::string portorservice)
: io_service_(),
thread_(boost::bind(&boost::asio::io_service::run, &io_service_)),
socket_(io_service_)
{
tcp::resolver resolver(io_service_);
tcp::resolver::query query(host, portorservice);
tcp::resolver::iterator iterator = resolver.resolve(query);
boost::asio::async_connect(socket_, iterator,
boost::bind(&chat_client::handle_connect, this,
boost::asio::placeholders::error));
}
void write(const chat_message& msg)
{
io_service_.post(boost::bind(&chat_client::do_write, this, msg));
}
void close()
{
io_service_.post(boost::bind(&chat_client::do_close, this));
}
~chat_client() {
close();
if (thread_.joinable())
thread_.join();
}
private:
void handle_connect(const boost::system::error_code& error)
{
if (!error)
{
boost::asio::async_read(socket_,
boost::asio::buffer(read_msg_.data(), chat_message::header_length),
boost::bind(&chat_client::handle_read_header, this,
boost::asio::placeholders::error));
}
}
void handle_read_header(const boost::system::error_code& error)
{
if (!error && read_msg_.decode_header())
{
boost::asio::async_read(socket_,
boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),
boost::bind(&chat_client::handle_read_body, this,
boost::asio::placeholders::error));
}
else
{
do_close();
}
}
void handle_read_body(const boost::system::error_code& error)
{
if (!error)
{
std::cout.write(read_msg_.body(), read_msg_.body_length());
std::cout << "\n";
boost::asio::async_read(socket_,
boost::asio::buffer(read_msg_.data(), chat_message::header_length),
boost::bind(&chat_client::handle_read_header, this,
boost::asio::placeholders::error));
}
else
{
do_close();
}
}
void do_write(chat_message msg)
{
bool write_in_progress = !write_msgs_.empty();
write_msgs_.push_back(msg);
if (!write_in_progress)
{
boost::asio::async_write(socket_,
boost::asio::buffer(write_msgs_.front().data(),
write_msgs_.front().length()),
boost::bind(&chat_client::handle_write, this,
boost::asio::placeholders::error));
}
}
void handle_write(const boost::system::error_code& error)
{
if (!error)
{
write_msgs_.pop_front();
if (!write_msgs_.empty())
{
boost::asio::async_write(socket_,
boost::asio::buffer(write_msgs_.front().data(),
write_msgs_.front().length()),
boost::bind(&chat_client::handle_write, this,
boost::asio::placeholders::error));
}
}
else
{
do_close();
}
}
void do_close()
{
socket_.close();
}
private:
boost::asio::io_service io_service_;
boost::thread thread_;
tcp::socket socket_;
chat_message read_msg_;
chat_message_queue write_msgs_;
};
int main(int argc, char* argv[])
{
try
{
if (argc != 3)
{
std::cerr << "Usage: chat_client <host> <port>\n";
return 1;
}
chat_client c(argv[1], argv[2]);
char line[chat_message::max_body_length + 1];
while (std::cin.getline(line, chat_message::max_body_length + 1))
{
using namespace std; // For strlen and memcpy.
chat_message msg;
msg.body_length(strlen(line));
memcpy(msg.body(), line, msg.body_length());
msg.encode_header();
c.write(msg);
}
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}
}