sigslot example w/shared_ptr

main.cpp

#include <thread>
#include <atomic>

#include <cstdio>
#include <chrono>

#include <memory>

#include <sigslot/signal.hpp>

///
/// Example with a ImageSource class that provides a imageSignal signal
/// That signal is connected to a slot in a WebServer instance, to receive 'images'
///
/// sigslot can keep track of objects' lifetime if they're shared_ptrs
/// 

class Thread
{
public:
    Thread() = default;
    virtual ~Thread()
    {
        if (m_thread.joinable())
            m_thread.join();
    }

    virtual void run() = 0;

    void start()
    {
        m_thread = std::move(std::thread(&Thread::run, this));
    }

    void join()
    {
        m_thread.join();
    }

private:
    std::thread m_thread;
};

class ImageSource : public Thread
{
public:

    ImageSource() = default;

    void run() override
    {
        using namespace std::chrono_literals;

        int i;
        while(true)
        {
            printf("ImageSource: emitting signal!\n");
            std::this_thread::sleep_for(0.5s);

            imageSignal(i++);
            if (i == 5)
                return;
        }
    }

    sigslot::signal<int> imageSignal;
};

class WebServer
{
public:
    WebServer() = default;

    void updateImage(int v)
    {
        printf("Web server: got image %d\n", v);
    }
};

int main()
{
    auto imageSource = std::make_shared<ImageSource>();
    auto webServer = std::make_shared<WebServer>();

    imageSource->imageSignal.connect(&WebServer::updateImage, webServer);

    imageSource->start();

    // we delete the slot in webServer and see how the library manages automatic disconnection
    using namespace std::chrono_literals;
    std::this_thread::sleep_for(1.1s);
    webServer.reset();

    // this will happen much later
    imageSource->join();
    return 0;
}