63 lines
2.3 KiB
Python
63 lines
2.3 KiB
Python
# -*- coding: utf-8 -*- #
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# Copyright 2022 Google LLC. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Simple immutable data object."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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from __future__ import unicode_literals
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import six
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class _DataType(type):
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"""Dumb immutable data type."""
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# TODO(b/154131605): This a type that is an immutable data object. Can't use
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# attrs because it's not part of googlecloudsdk and can't use namedtuple
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# because it's not efficient on python 2 (it generates code, which needs
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# to be parsed and interpretted). Remove this code when we get support
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# for attrs or another dumb data object in gcloud.
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def __new__(cls, classname, bases, class_dict):
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class_dict = class_dict.copy()
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names = class_dict.get('NAMES', tuple())
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class_dict.update(
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(name, cls._CreateAccessor(i)) for i, name in enumerate(names))
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return super(_DataType, cls).__new__(cls, classname, bases, class_dict)
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@staticmethod
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def _CreateAccessor(i):
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"""Create an tuple accessor property."""
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return property(lambda tpl: tpl[i]) # pylint: disable=unused-variable
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class DataObject(six.with_metaclass(_DataType, tuple)):
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"""Parent class of dumb data object."""
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def __new__(cls, **kwargs):
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names = getattr(cls, 'NAMES', tuple())
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invalid_names = set(kwargs) - set(names)
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if invalid_names:
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raise ValueError('Invalid names: ' + repr(invalid_names))
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tpl = tuple(kwargs[name] if name in kwargs else None for name in names)
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return super(DataObject, cls).__new__(cls, tpl)
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def replace(self, **changes): # pylint: disable=invalid-name
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# https://docs.python.org/3/library/dataclasses.html#dataclasses.replace
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out = dict((n, changes.get(n, getattr(self, n, None))) for n in self.NAMES)
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return self.__class__(**out)
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