deviceMethodWidget.py: avoid temporal coupling in the method `control_changed`

kamzik3/gui/deviceMethodWidget.py

@@ -231,7 +231,6 @@ class MethodEnabledByAttributeWidget(DeviceMethodEnabledWidget):
         parent=None,
     ) -> None:
         self.external_device_attribute = external_device_attribute
-        self._editable_widgets: List[int] = []
         super().__init__(
             device=device,
             method=method,
@@ -244,15 +243,17 @@ class MethodEnabledByAttributeWidget(DeviceMethodEnabledWidget):
         """
         Slot executed when a signal is emitted from `sig_control_changed`.
         """
+        editable_widgets = self._find_editable_widgets()
         if self.input_value is not None:
-            for index in self._editable_widgets:
+            for index in editable_widgets:
                 if value:
                     self.input_value.children()[index].setEnabled(False)  # type: ignore
                 else:
                     self.input_value.children()[index].setEnabled(True)  # type: ignore
 
-    def _find_editable_widgets(self) -> None:
+    def _find_editable_widgets(self) -> List[int]:
         """Find the indices of the input fields that should be enabled/disabled"""
+        editable_widgets: List[int] = []
         if self.input_value is not None:
             for idx, child in enumerate(self.input_value.children()):
                 if type(child) == QWidget:  # pylint: disable=unidiomatic-typecheck
@@ -260,8 +261,9 @@ class MethodEnabledByAttributeWidget(DeviceMethodEnabledWidget):
                     # inherited from it
                     for grandchild in child.children():
                         if isinstance(grandchild, (QSpinBox, QDoubleSpinBox)):
-                            self._editable_widgets.append(idx)
+                            editable_widgets.append(idx)
                             break
+        return editable_widgets
 
     def init_signals(self) -> None:
         """