Convert on_trait_change decorators to observe decorators

examples/application/python_editor/python_editor_task.py

@@ -54,7 +54,7 @@
     Property,
     Str,
     cached_property,
-    on_trait_change,
+    observe,
 )
 
 from python_browser_pane import PythonBrowserPane
@@ -333,15 +333,16 @@ def _prompt_for_save(self):
 
     # Trait change handlers --------------------------------------------------
 
-    @on_trait_change("window:closing")
+    @observe("window:closing")
     def _prompt_on_close(self, event):
         """ Prompt the user to save when exiting.
         """
         close = self._prompt_for_save()
-        event.veto = not close
+        window = event.new
+        window.veto = not close
 
-    @on_trait_change("active_editor.name")
-    def _change_title(self):
+    @observe("active_editor.name")
+    def _change_title(self, event):
         """ Update the window title when the active editor changes.
         """
         if self.window.active_task == self:
@@ -350,8 +351,8 @@ def _change_title(self):
             else:
                 self.window.title = self.name
 
-    @on_trait_change("active_editor.[line,column,selection_length]")
-    def _update_status(self):
+    @observe("active_editor.[line,column,selection_length]")
+    def _update_status(self, event):
         if self.active_editor is not None:
             editor = self.active_editor
             if editor.selection_length:

examples/tasks/advanced/example_task.py

@@ -21,7 +21,7 @@
     OK,
     CANCEL,
 )
-from traits.api import on_trait_change, Property, Instance
+from traits.api import observe, Property, Instance
 
 
 from example_panes import PythonScriptBrowserPane
@@ -185,12 +185,13 @@ def _prompt_for_save(self):
 
     # Trait change handlers ------------------------------------------------
 
-    @on_trait_change("window:closing")
+    @observe("window:closing")
     def _prompt_on_close(self, event):
         """ Prompt the user to save when exiting.
         """
         close = self._prompt_for_save()
-        event.veto = not close
+        window = event.new
+        window.veto = not close
 
     # Trait property getter/setters ----------------------------------------
 

examples/tasks/basic/example_task.py

@@ -14,7 +14,7 @@
     OK,
     CANCEL,
 )
-from traits.api import on_trait_change
+from traits.api import observe
 
 
 from example_panes import PythonEditorPane, PythonScriptBrowserPane
@@ -148,9 +148,10 @@ def _prompt_for_save(self):
                     return self._prompt_for_save()
         return True
 
-    @on_trait_change("window:closing")
+    @observe("window:closing")
     def _prompt_on_close(self, event):
         """ Prompt the user to save when exiting.
         """
+        window = event.new
         if not self._prompt_for_save():
-            event.veto = True
+            window.veto = True

pyface/action/action_item.py

@@ -11,7 +11,7 @@
 """ An action manager item that represents an actual action. """
 
 
-from traits.api import Any, Instance, List, Property, Str, on_trait_change
+from traits.api import Any, Instance, List, Property, Str, observe
 
 
 from pyface.action.action import Action
@@ -72,11 +72,11 @@ def _enabled_changed(self, trait_name, old, new):
     def _visible_changed(self, trait_name, old, new):
         self.action.visible = new
 
-    @on_trait_change("_wrappers.control")
-    def _on_destroy(self, object, name, old, new):
+    @observe("_wrappers:items:control")
+    def _on_destroy(self, event):
         """ Handle the destruction of the wrapper. """
-        if name == "control" and new is None:
-            self._wrappers.remove(object)
+        if event.new is None:
+            self._wrappers.remove(event.object)
 
     # ------------------------------------------------------------------------
     # 'ActionItem' interface.

pyface/data_view/data_models/row_table_data_model.py

@@ -14,7 +14,7 @@
 """
 from collections.abc import Sequence
 
-from traits.api import ComparisonMode, Instance, List, observe
+from traits.api import Instance, List, observe
 from traits.observation.api import trait
 
 from pyface.data_view.abstract_data_model import (
@@ -35,20 +35,13 @@ class RowTableDataModel(AbstractDataModel):
     """
 
     #: A sequence of objects to display as rows.
-    data = Instance(
-        Sequence,
-        comparison_mode=ComparisonMode.identity,
-        allow_none=False,
-    )
+    data = Instance(Sequence, allow_none=False)
 
     #: An object which describes how to map data for the row headers.
     row_header_data = Instance(AbstractDataAccessor, allow_none=False)
 
     #: An object which describes how to map data for each column.
-    column_data = List(
-        Instance(AbstractDataAccessor, allow_none=False),
-        comparison_mode=ComparisonMode.identity,
-    )
+    column_data = List(Instance(AbstractDataAccessor, allow_none=False))
 
     #: The index manager that helps convert toolkit indices to data view
     #: indices.

pyface/data_view/i_data_view_widget.py

@@ -12,7 +12,7 @@
 import logging
 
 from traits.api import (
-    Bool, ComparisonMode, Enum, HasStrictTraits, Instance, List, Property,
+    Bool, Enum, HasStrictTraits, Instance, List, Property,
     TraitError, Tuple, cached_property,
 )
 
@@ -53,10 +53,7 @@ class IDataViewWidget(IWidget):
     selection = List(Tuple)
 
     #: Exporters available for the DataViewWidget.
-    exporters = List(
-        Instance(AbstractDataExporter),
-        comparison_mode=ComparisonMode.identity,
-    )
+    exporters = List(Instance(AbstractDataExporter))
 
 
 class MDataViewWidget(HasStrictTraits):
@@ -81,10 +78,7 @@ class MDataViewWidget(HasStrictTraits):
     selection = Property(depends_on='_selection[]')
 
     #: Exporters available for the DataViewWidget.
-    exporters = List(
-        Instance(AbstractDataExporter),
-        comparison_mode=ComparisonMode.identity,
-    )
+    exporters = List(Instance(AbstractDataExporter))
 
     # Private traits --------------------------------------------------------
 
@@ -93,7 +87,7 @@ class MDataViewWidget(HasStrictTraits):
 
     #: The selected indices in the view.  This should never be mutated, any
     #: changes should be by replacement of the entire list.
-    _selection = List(Tuple, comparison_mode=ComparisonMode.identity)
+    _selection = List(Tuple)
 
     # ------------------------------------------------------------------------
     # MDataViewWidget Interface

pyface/gui_application.py

@@ -31,7 +31,7 @@
     Tuple,
     Undefined,
     Vetoable,
-    on_trait_change,
+    observe,
 )
 
 from .application import Application
@@ -280,22 +280,22 @@ def _about_dialog_default(self):
 
     # Trait listeners --------------------------------------------------------
 
-    @on_trait_change("windows:activated")
-    def _on_activate_window(self, window, trait, old, new):
+    @observe("windows:items:activated")
+    def _on_activate_window(self, event):
         """ Listener that tracks currently active window.
         """
-        if window in self.windows:
-            self.active_window = window
+        if event.object in self.windows:
+            self.active_window = event.object
 
-    @on_trait_change("windows:deactivated")
-    def _on_deactivate_window(self, window, trait, old, new):
+    @observe("windows:items:deactivated")
+    def _on_deactivate_window(self, event):
         """ Listener that tracks currently active window.
         """
         self.active_window = None
 
-    @on_trait_change("windows:closed")
-    def _on_window_closed(self, window, trait, old, new):
+    @observe("windows:items:closed")
+    def _on_window_closed(self, event):
         """ Listener that ensures window handles are released when closed.
         """
-        if window in self.windows:
-            self.windows.remove(window)
+        if event.object in self.windows:
+            self.windows.remove(event.object)

pyface/tasks/action/dock_pane_toggle_group.py

@@ -15,7 +15,7 @@
     cached_property,
     Instance,
     List,
-    on_trait_change,
+    observe,
     Property,
     Str,
 )
@@ -66,13 +66,13 @@ def _get_name(self):
     def _get_tooltip(self):
         return "Toggles the visibility of the %s pane." % self.name
 
-    @on_trait_change("dock_pane.visible")
-    def _update_checked(self):
+    @observe("dock_pane.visible")
+    def _update_checked(self, event):
         if self.dock_pane:
             self.checked = self.dock_pane.visible
 
-    @on_trait_change("dock_pane.closable")
-    def _update_visible(self):
+    @observe("dock_pane.closable")
+    def _update_visible(self, event):
         if self.dock_pane:
             self.visible = self.dock_pane.closable
 
@@ -119,8 +119,8 @@ def get_manager(self):
 
     # Private interface ----------------------------------------------------
 
-    @on_trait_change("dock_panes[]")
-    def _dock_panes_updated(self):
+    @observe("dock_panes.items")
+    def _dock_panes_updated(self, event):
         """Recreate the group items when dock panes have been added/removed.
         """
 

pyface/tasks/action/task_toggle_group.py

@@ -10,7 +10,7 @@
 
 
 from pyface.action.api import Action, ActionItem, Group
-from traits.api import Any, List, Instance, Property, Str, on_trait_change
+from traits.api import Any, List, Instance, Property, Str, observe
 
 
 from pyface.tasks.task import Task
@@ -65,8 +65,8 @@ def _get_name(self):
     def _get_tooltip(self):
         return "Switch to the %s task." % self.name
 
-    @on_trait_change("task.window.active_task")
-    def _update_checked(self):
+    @observe("task.window.active_task")
+    def _update_checked(self, event):
         if self.task:
             window = self.task.window
             self.checked = (

pyface/tasks/action/task_window_toggle_group.py

@@ -10,7 +10,7 @@
 
 
 from pyface.action.api import Action, ActionItem, Group
-from traits.api import Any, Instance, List, Property, Str, on_trait_change
+from traits.api import Any, Instance, List, Property, Str, observe
 
 
 class TaskWindowToggleAction(Action):
@@ -47,12 +47,12 @@ def _get_name(self):
             return self.window.title
         return ""
 
-    @on_trait_change("window:activated")
-    def _window_activated(self):
+    @observe("window:activated")
+    def _window_activated(self, event):
         self.checked = True
 
-    @on_trait_change("window:deactivated")
-    def _window_deactivated(self):
+    @observe("window:deactivated")
+    def _window_deactivated(self, event):
         self.checked = False
 
 

pyface/tasks/task_window.py

@@ -23,7 +23,7 @@
     Property,
     Str,
     Vetoable,
-    on_trait_change,
+    observe,
 )
 
 
@@ -431,13 +431,13 @@ def __active_state_changed(self, state):
             self.status_bar_manager = state.status_bar_manager
             self.tool_bar_managers = state.tool_bar_managers
 
-    @on_trait_change("central_pane.has_focus, dock_panes.has_focus")
-    def _focus_updated(self, obj, name, old, new):
-        if name == "has_focus" and new:
-            self.active_pane = obj
+    @observe("central_pane:has_focus, dock_panes:items:has_focus")
+    def _focus_updated(self, event):
+        if event.new:
+            self.active_pane = event.object
 
-    @on_trait_change("_states[]")
-    def _states_updated(self):
+    @observe("_states.items")
+    def _states_updated(self, event):
         self.tasks = [state.task for state in self._states]
 
 

pyface/tasks/tasks_application.py

@@ -23,7 +23,7 @@
     Property,
     Str,
     cached_property,
-    on_trait_change,
+    observe,
 )
 
 from pyface.gui_application import GUIApplication
@@ -172,15 +172,14 @@ def _get_task_factory(self, id):
 
     # Destruction utilities ---------------------------------------------------
 
-    @on_trait_change("windows:closed")
-    def _on_window_closed(self, window, trait, old, new):
+    @observe("windows:items:closed")
+    def _on_window_closed(self, event):
         """ Listener that ensures window handles are released when closed.
         """
+        window = event.object
         if getattr(window, "active_task", None) in self.tasks:
             self.tasks.remove(window.active_task)
-        super(TasksApplication, self)._on_window_closed(
-            window, trait, old, new
-        )
+        super(TasksApplication, self)._on_window_closed(event)
 
     # Trait initializers and property getters ---------------------------------
 

pyface/tests/test_gui_application.py

@@ -14,7 +14,7 @@
 from tempfile import mkdtemp
 import unittest
 
-from traits.api import Bool, on_trait_change
+from traits.api import Bool, observe
 
 from ..application_window import ApplicationWindow
 from ..gui_application import GUIApplication
@@ -104,10 +104,10 @@ def _prepare_exit(self):
         if self.exit_prepared_error:
             raise Exception("Exit preparation failed")
 
-    @on_trait_change("windows:opening")
+    @observe("windows:items:opening")
     def _on_activate_window(self, event):
         if self.veto_open_window:
-            event.veto = self.veto_open_window
+            event.new.veto = self.veto_open_window
 
 
 @unittest.skipIf(no_gui_test_assistant, "No GuiTestAssistant")