New NotiferInterface class, for describing the interface used to notify different components within Bloom, of any important events.

src/Helpers/NotifierInterface.hpp

@@ -0,0 +1,37 @@
+#pragma once
+
+namespace Bloom
+{
+    /**
+     * The NotifierInterface class describes an interface for notifying different components, within Bloom, of something
+     * important that has just happened.
+     *
+     * It's important to note that this interface only describes the issuing of notifications. It *does not* describe
+     * the listening for notifications. The listening can be defined by the implementation.
+     *
+     * For example, consider the EventFdNotifier implementation. That class is just an RAII wrapper for a Linux eventfd
+     * object. Notifications are recorded by incrementing the eventfd counter. And they can be listened for, using
+     * Linux system functions like poll(), select(), and similar.
+     *
+     * The EventListener class can hold a pointer to a NotifierInterface, where it will invoke
+     * NotifierInterface::notify() everytime a new event is registered on the listener.
+     */
+    class NotifierInterface
+    {
+    public:
+        NotifierInterface() = default;
+        virtual ~NotifierInterface() noexcept = default;
+
+        NotifierInterface(NotifierInterface& other) = delete;
+
+        NotifierInterface& operator = (NotifierInterface& other) = delete;
+        NotifierInterface& operator = (NotifierInterface&& other) = delete;
+
+        NotifierInterface(NotifierInterface&& other) noexcept = default;
+
+        /**
+         * Should record a notification.
+         */
+        virtual void notify() = 0;
+    };
+}