48 lines
1.7 KiB
Python
48 lines
1.7 KiB
Python
# Copyright (c) 2011-2013 OpenStack Foundation.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# 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, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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A common base for handling extension classes.
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Used by BaseFilterHandler and BaseWeightHandler
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"""
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import inspect
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from stevedore import extension
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class BaseHandler(object):
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"""Base class to handle loading filter and weight classes."""
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def __init__(self, modifier_class_type, modifier_namespace):
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self.namespace = modifier_namespace
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self.modifier_class_type = modifier_class_type
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self.extension_manager = extension.ExtensionManager(modifier_namespace)
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def _is_correct_class(self, cls):
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"""Return whether an object is a class of the correct type.
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(or is not prefixed with an underscore)
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"""
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return (inspect.isclass(cls) and
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not cls.__name__.startswith('_') and
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issubclass(cls, self.modifier_class_type))
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def get_all_classes(self):
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# We use a set, as some classes may have an entrypoint of their own,
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# and also be returned by a function such as 'all_filters' for example
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return [ext.plugin for ext in self.extension_manager if
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self._is_correct_class(ext.plugin)]
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