Source code for pyface.undo.action.abstract_command_stack_action

# (C) Copyright 2008-2022 Enthought, Inc., Austin, TX
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# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
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# ------------------------------------------------------------------------------
# Copyright (c) 2008, Riverbank Computing Limited
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in enthought/LICENSE.txt and may be redistributed only
# under the conditions described in the aforementioned license.  The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
# Thanks for using Enthought open source!
#
# Author: Riverbank Computing Limited
# Description: <Enthought undo package component>
# ------------------------------------------------------------------------------

# Enthought library imports.
from pyface.action.api import Action
from traits.api import Instance

# Local library imports
from ..i_undo_manager import IUndoManager


[docs]class AbstractCommandStackAction(Action): """The abstract base class for all actions that operate on a command stack. """ #### 'AbstractCommandStackAction' interface ############################### #: The undo manager. undo_manager = Instance(IUndoManager) ########################################################################### # 'object' interface. ########################################################################### def __init__(self, **traits): """ Initialise the instance. """ super().__init__(**traits) self.undo_manager.observe( self._on_stack_updated, "stack_updated" ) # Update the action to initialise it. self._update_action() ########################################################################### # 'Action' interface. ###########################################################################
[docs] def destroy(self): """Called when the action is no longer required. By default this method does nothing, but this would be a great place to unhook trait listeners etc. """ self.undo_manager.observe( self._on_stack_updated, "stack_updated", remove=True )
########################################################################### # Protected interface. ########################################################################### def _update_action(self): """ Update the state of the action. """ raise NotImplementedError ########################################################################### # Private interface. ########################################################################### def _on_stack_updated(self, event): """ Handle changes to the state of a command stack. """ stack = event.new # Ignore unless it is the active stack. if stack is self.undo_manager.active_stack: self._update_action()