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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>
#------------------------------------------------------------------------------
from __future__ import absolute_import
# Enthought library imports.
from pyface.action.api import Action
from traits.api import Instance
# Local library imports
from ..i_undo_manager import IUndoManager
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(AbstractCommandStackAction, self).__init__(**traits)
self.undo_manager.on_trait_event(self._on_stack_updated, 'stack_updated')
# Update the action to initialise it.
self._update_action()
###########################################################################
# 'Action' interface.
###########################################################################
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.on_trait_event(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, stack):
""" Handle changes to the state of a command stack. """
# Ignore unless it is the active stack.
if stack is self.undo_manager.active_stack:
self._update_action()
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