118f7ea84a
There are many scenarios in different projects that end up needing this support. We should gently nudge everyone to move to Stevedore but can't mandate it by hiding these methods. Change-Id: Ie2783fabf52491a490c999728995da8e68e62cd8
74 lines
2.3 KiB
Python
74 lines
2.3 KiB
Python
# Copyright 2011 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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Import related utilities and helper functions.
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"""
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import sys
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import traceback
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def import_class(import_str):
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"""Returns a class from a string including module and class."""
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mod_str, _sep, class_str = import_str.rpartition('.')
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__import__(mod_str)
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try:
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return getattr(sys.modules[mod_str], class_str)
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except AttributeError:
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raise ImportError('Class %s cannot be found (%s)' %
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(class_str,
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traceback.format_exception(*sys.exc_info())))
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def import_object(import_str, *args, **kwargs):
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"""Import a class and return an instance of it."""
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return import_class(import_str)(*args, **kwargs)
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def import_object_ns(name_space, import_str, *args, **kwargs):
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"""Tries to import object from default namespace.
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Imports a class and return an instance of it, first by trying
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to find the class in a default namespace, then failing back to
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a full path if not found in the default namespace.
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"""
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import_value = "%s.%s" % (name_space, import_str)
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try:
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return import_class(import_value)(*args, **kwargs)
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except ImportError:
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return import_class(import_str)(*args, **kwargs)
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def import_module(import_str):
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"""Import a module."""
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__import__(import_str)
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return sys.modules[import_str]
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def import_versioned_module(version, submodule=None):
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module = 'oslo.v%s' % version
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if submodule:
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module = '.'.join((module, submodule))
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return import_module(module)
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def try_import(import_str, default=None):
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"""Try to import a module and if it fails return default."""
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try:
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return import_module(import_str)
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except ImportError:
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return default
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