started working on template-policy based implementation of add_task().

thread_pool.hpp

@@ -52,6 +52,24 @@ class thread_pool
     /* the main loop of the threads */
     void loop();
 
+    class place_front_policy
+    {
+    public:
+        template <typename F, typename... Args>
+        static void place(std::shared_ptr<std::packaged_task<decltype(std::declval<F>()(std::declval<Args>()...))>> task,
+                          std::deque<std::function<void()>>& queue, std::mutex& mu)
+        {
+            {
+                std::lock_guard<std::mutex> lock(mu);
+                queue.emplace_back([task](){ (*task)(); });
+            }
+        }
+    };
+
+    template <typename F, typename... Args, class placement_policy = place_front_policy>
+    auto _add_task_internal(F&& f, Args&&... args) -> std::future<decltype(f(std::forward<Args>(args)...))>;
+
+
 public:
 
     /* construction & destruction */
@@ -89,6 +107,19 @@ public:
 
 };
 
+template <typename F, typename... Args, class placement_policy>
+auto thread_pool::_add_task_internal(F&& f, Args&&... args)
+-> std::future<decltype(f(std::forward<Args>(args)...))>
+{
+    auto pckgd_tsk = std::make_shared<std::packaged_task<decltype(f(std::forward<Args>(args)...))()> >
+            (std::bind(std::forward<F>(f), std::forward<Args>(args)...));
+
+    placement_policy::place(pckgd_tsk, queue, mu);
+    cond.notify_one();
+
+    return pckgd_tsk->get_future();
+}
+
 thread_pool::thread_pool(size_t thcount):
         fin(false)
 {