Merge pull request #74 from enthought/action-schema

Schema for Pyface Actions.

pyface/tasks/action/api.py

@@ -1,7 +1,7 @@
 # Local imports.
 from dock_pane_toggle_group import DockPaneToggleGroup
-from schema import GroupSchema, MenuSchema, MenuBarSchema, ToolBarSchema, \
-     SGroup, SMenu, SMenuBar, SToolBar
+from schema import ActionSchema, GroupSchema, MenuSchema, MenuBarSchema, \
+    ToolBarSchema, SGroup, SMenu, SMenuBar, SToolBar
 from schema_addition import SchemaAddition
 from task_action import CentralPaneAction, DockPaneAction, EditorAction, \
      TaskAction, TaskWindowAction

pyface/tasks/action/schema.py

@@ -2,7 +2,7 @@
 from pyface.action.api import Action, ActionItem, Group, \
      MenuManager, MenuBarManager, ToolBarManager
 from traits.api import Bool, Callable, Enum, HasTraits, Instance, \
-     List, Str, Trait, Tuple, Unicode
+     List, Property, Str, Trait, Tuple, Unicode
 
 # Trait definitions.
 SubSchema = Trait(None, Action, ActionItem, Group, MenuManager,
@@ -35,6 +35,33 @@ def create(self, children):
         raise NotImplementedError
 
 
+class ActionSchema(Schema):
+    """ Action schema for Pyface Actions.
+
+    An action schema cannot have children. It is used as an action factory
+    to make sure a larger schema (e.g., a menu schema) can be used multiple
+    times. Without using an ActionSchema, a reference to the action is added
+    to every menu created from the schema. When one of the menus is destroyed,
+    the action is also destroyed and is made unusable.
+
+    """
+
+    #: A factory for the Action instance.
+    action_factory = Callable(Action)
+
+    #: Items is overwritten to be empty and read-only to avoid assigning to
+    #: it by mistake.
+    items = Property()
+    def _get_items(self):
+        return []
+
+    def create(self, children):
+        """ Create the appropriate PyFace Action instance. """
+
+        traits = dict(id=self.id)
+        return self.action_factory(**traits)
+
+
 class GroupSchema(Schema):
     """ A schema for a Pyface Group.
     """