create new singleton class

cockatrice/CMakeLists.txt

@@ -31,6 +31,7 @@ set(cockatrice_SOURCES
     src/server/chat_view/chat_view.cpp
     src/game/board/counter_general.cpp
     src/deck/custom_line_edit.cpp
+    src/deck/deck_edit_event_bus.cpp
     src/deck/deck_loader.cpp
     src/deck/deck_list_model.cpp
     src/deck/deck_stats_interface.cpp

cockatrice/src/deck/deck_edit_event_bus.cpp

@@ -0,0 +1,14 @@
+#include "deck_edit_event_bus.h"
+
+DeckEditEventBus::DeckEditEventBus()
+{
+}
+
+/**
+ * Gets the singleton instance of the event bus
+ */
+DeckEditEventBus *DeckEditEventBus::instance()
+{
+    static DeckEditEventBus deckEditEventBus; // Created only once, on first access
+    return &deckEditEventBus;
+}

cockatrice/src/deck/deck_edit_event_bus.h

@@ -0,0 +1,26 @@
+#ifndef DECK_EDIT_EVENT_BUS_H
+#define DECK_EDIT_EVENT_BUS_H
+
+#include <QObject>
+
+/**
+ * A singleton object that can be used to pass signals between objects that are far apart in the object tree.
+ * Contains signals that are related to deck editor and deck storage.
+ */
+class DeckEditEventBus : public QObject
+{
+    Q_OBJECT
+
+private:
+    // hide constructor
+    explicit DeckEditEventBus();
+
+    // Delete copy constructor and assignment operator to enforce singleton
+    DeckEditEventBus(const DeckEditEventBus &) = delete;
+    DeckEditEventBus &operator=(const DeckEditEventBus &) = delete;
+
+public:
+    static DeckEditEventBus *instance();
+};
+
+#endif // DECK_EDIT_EVENT_BUS_H