Code Widget refactor; observable refactor

src/libs/mixins/observable_mixin.py

@@ -0,0 +1,26 @@
+# Python imports
+
+# Lib imports
+
+# Application imports
+from ..dto.observable_event import ObservableEvent
+
+
+
+class ObservableMixin:
+    observers = []
+
+    def add_observer(self, observer: any):
+        if not hasattr(observer, 'notification') or not callable(getattr(observer, 'notification')):
+            raise ValueError(f"Observer '{observer}' must implement a `notification` method.")
+
+        self.observers.append(observer)
+
+    def remove_observer(self, observer: any):
+        if not observer in self.observers: return
+
+        self.observers.remove(observer)
+
+    def notify_observers(self, event: ObservableEvent):
+        for observer in self.observers:
+            observer.notification(event)