Separating Library Includes From Program Using Library

Question

I am creating a DLL library which will export some functions to be used in other C++ projects. In my library, I am using precompiled headers, as well as Boost ASIO. However, I want to know if it is possible to contain all ASIO related things within the library itself so that the other program does not need to include them. For example:

stdafx.h (library):

#pragma once

#include "targetver.h"

#define WIN32_LEAN_AND_MEAN

#include <Windows.h>
#include <WinSock2.h>
#include <iostream>
#include <string.h>

#pragma comment(lib, "ws2_32")

#include <boost/asio.hpp>

Client.h (library):

#pragma once

#ifdef LIB_EXPORTS
#define LIB_API __declspec(dllexport)
#else
#define LIB_API __declspec(dllimport)
#endif

using boost::asio::ip::tcp;

namespace TestLib {
    class Client {
        boost::asio::io_service io_service_;
        tcp::resolver resolver_;
        tcp::socket socket_;

    public:
        LIB_API Client();

        LIB_API bool Connect(const std::string& szHost, const std::string& szPort);

        virtual ~Client();
    };
}

However, in my program that uses this library, I want to be able to include Client.h without also having to include Boost ASIO. Because I include this header without including Boost ASIO, I get errors about all of the lines in Client.h that reference Boost utilities, such as the using statement and the three private member variables.

How do I go about creating the library in such a way so that my other program only needs to include Client.h, for example?

Search for pimpl on this site. It's one way to hide implementation details so you can eliminate include dependencies. — Anon Mail, Nov 17 '15 at 05:45

score 0 · Accepted Answer · answered Nov 18 '15 at 19:31

I have solved my problem using Anon Mail's suggestion. Here is the solution:

Client.h (library):

#pragma once

#ifdef LIB_EXPORTS
#define LIB_API __declspec(dllexport)
#else
#define LIB_API __declspec(dllimport)
#endif

namespace TestLib {
    class Client {
        struct Imp;
        std::unique_ptr<Imp> imp_;

    public:
        LIB_API Client();

        LIB_API bool Connect(const std::string& szHost, const std::string& szPort);

        LIB_API virtual ~Client();
    };
}

Client.cpp (library):

namespace TestLib {
    struct Client::Imp {
        Client::Imp() : 
            io_service_(new boost::asio::io_service()), 
            resolver_(new tcp::resolver(*io_service_)),
            socket_(new tcp::socket(*io_service_)) {

        }

        std::shared_ptr<boost::asio::io_service> io_service_;
        std::shared_ptr<tcp::resolver> resolver_;
        std::shared_ptr<tcp::socket> socket_;
    };

    Client::Client() : imp_(new Imp) {
    }

    bool Client::Connect(const std::string& szHost, const std::string& szPort) {
        tcp::resolver::query query(szHost, szPort);

        tcp::resolver::iterator endpoint_iter = imp_->resolver_->resolve(query);

        boost::asio::connect(*imp_->socket_, endpoint_iter);

        return true;
    }
}

Forgive me if I'm using the wrong types of pointers. Any guidance on this solution would be much appreciated!

Separating Library Includes From Program Using Library

1 Answers1