Re: How to update both the Console and the GTKMM gui window after running other functions

[Andrew Potter <agpotter gmail com>]

On Thu, Aug 1, 2013 at 9:52 AM, Alan Mazer <alan s mazer jpl nasa gov> wrote:
> P.S.  I don't know why it doesn't take arguments either, but one can work
> around that with globals and a mutex.

There's actually a really nice solution I've been using lately. It
uses C++11, but it can be rewritten using only glib/sigc++.

    class CallbackDispatcher {
    public:
        CallbackDispatcher(const CallbackDispatcher&) = delete;
        CallbackDispatcher& operator=(const CallbackDispatcher&) = delete;

        CallbackDispatcher() {
            m_dispatcher.connect(sigc::mem_fun(*this,

&CallbackDispatcher::on_dispatch));
        };

        template<typename Fn>
        void operator()(Fn&& fn) {
            std::lock_guard<std::mutex> lock(m_mutex);
            m_msgs.push(std::forward<Fn>(fn));
            m_dispatcher();
        }

    private:
        typedef std::function<void ()> Callback;

        std::queue<Callback> m_msgs;
        mutable std::mutex   m_mutex;
        Glib::Dispatcher     m_dispatcher;

        void on_dispatch() {
            std::lock_guard<std::mutex> lock(m_mutex);
            while (!m_msgs.empty()) {
                m_msgs.front()();
                m_msgs.pop();
            }
        }
    };


Usage:

void my_fun(Param one, Param two) {
  // Whatever should be run in main loop
}

void my_threaded_fun() {
// This is running on a separate thread
Param one, two;
callbackDispatcher(std::bind(&my_fun, one, two));
// The bound function is added to the callback_dispatchers queue, the
dispatcher is called. In the main loop eventually the queue is served
and the callback is called with the bound parameters!
}

What's nice about this pattern is that you only need one dispatcher
for any number of callbacks.

Also its nice to just throw a lambda in there..