adds warning message when super().__init__() is not called at the start of the constructor

src/pydase/observer_pattern/observable/observable.py

@@ -22,10 +22,15 @@ class Observable(ObservableObject):
             self.__dict__[name] = self._initialise_new_objects(name, value)
 
     def __setattr__(self, name: str, value: Any) -> None:
-        if hasattr(self, "_observers"):
-            self._remove_observer_if_observable(name)
-            value = self._initialise_new_objects(name, value)
-            self._notify_change_start(name)
+        if not hasattr(self, "_observers") and name != "_observers":
+            logger.warning(
+                "Ensure that super().__init__() is called at the start of the '%s' "
+                "constructor! Failing to do so may lead to unexpected behavior.",
+                type(self).__name__,
+            )
+            self._observers = {}
+
+        value = self._handle_observable_setattr(name, value)
 
         super().__setattr__(name, value)
 
@@ -42,6 +47,15 @@ class Observable(ObservableObject):
 
         return value
 
+    def _handle_observable_setattr(self, name: str, value: Any) -> Any:
+        if name == "_observers":
+            return value
+
+        self._remove_observer_if_observable(name)
+        value = self._initialise_new_objects(name, value)
+        self._notify_change_start(name)
+        return value
+
     def _remove_observer_if_observable(self, name: str) -> None:
         if not is_property_attribute(self, name):
             current_value = getattr(self, name, None)

src/pydase/observer_pattern/observable/observable_object.py

@@ -13,7 +13,8 @@ class ObservableObject(ABC):
     _dict_mapping: ClassVar[dict[int, "_ObservableDict"]] = {}
 
     def __init__(self) -> None:
-        self._observers: dict[str, list["ObservableObject | Observer"]] = {}
+        if not hasattr(self, "_observers"):
+            self._observers: dict[str, list["ObservableObject | Observer"]] = {}
 
     def add_observer(
         self, observer: "ObservableObject | Observer", attr_name: str = ""

tests/observer_pattern/observable/test_observable.py

@@ -13,6 +13,20 @@ class MyObserver(Observer):
         logger.info("'%s' changed to '%s'", full_access_path, value)
 
 
+def test_constructor_error_message(caplog: pytest.LogCaptureFixture) -> None:
+    class MyObservable(Observable):
+        def __init__(self) -> None:
+            self.attr = 1
+            super().__init__()
+
+    MyObservable()
+
+    assert (
+        "Ensure that super().__init__() is called at the start of the 'MyObservable' "
+        "constructor! Failing to do so may lead to unexpected behavior." in caplog.text
+    )
+
+
 def test_simple_class_attribute(caplog: pytest.LogCaptureFixture) -> None:
     class MyObservable(Observable):
         int_attribute = 10