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# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import abc
import inspect
import six
from cliff import argparse
@six.add_metaclass(abc.ABCMeta)
class Command(object):
"""Base class for command plugins.
:param app: Application instance invoking the command.
:paramtype app: cliff.app.App
"""
deprecated = False
_description = ''
def __init__(self, app, app_args, cmd_name=None):
self.app = app
self.app_args = app_args
self.cmd_name = cmd_name
return
def get_description(self):
"""Return the command description.
The default is to use the first line of the class' docstring
as the description. Set the ``_description`` class attribute
to a one-line description of a command to use a different
value. This is useful for enabling translations, for example,
with ``_description`` set to a string wrapped with a gettext
translation marker.
"""
# NOTE(dhellmann): We need the trailing "or ''" because under
# Python 2.7 the default for the docstring is None instead of
# an empty string, and we always want this method to return a
# string.
desc = self._description or inspect.getdoc(self.__class__) or ''
# The base class command description isn't useful for any
# real commands, so ignore that value.
if desc == inspect.getdoc(Command):
desc = ''
return desc
def get_parser(self, prog_name):
"""Return an :class:`argparse.ArgumentParser`.
"""
parser = argparse.ArgumentParser(
description=self.get_description(),
prog=prog_name,
)
return parser
@abc.abstractmethod
def take_action(self, parsed_args):
"""Override to do something useful.
The returned value will be returned by the program.
"""
def run(self, parsed_args):
"""Invoked by the application when the command is run.
Developers implementing commands should override
:meth:`take_action`.
Developers creating new command base classes (such as
:class:`Lister` and :class:`ShowOne`) should override this
method to wrap :meth:`take_action`.
Return the value returned by :meth:`take_action` or 0.
"""
return self.take_action(parsed_args) or 0
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