102 lines
2.9 KiB
Python
102 lines
2.9 KiB
Python
# Copyright 2014 - Dark Secret Software Inc.
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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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import imp
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import logging
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import os
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import os.path
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import sys
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LOG = logging.getLogger(__name__)
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class MissingModule(Exception):
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pass
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class BadDirectory(Exception):
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pass
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class MissingMethodOrFunction(Exception):
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pass
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class ImportFailed(Exception):
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pass
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def _get_module(target):
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"""Import a named class, module, method or function.
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Accepts these formats:
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".../file/path|module_name:Class.method"
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".../file/path|module_name:function"
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If a fully qualified file is specified, it implies the
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file is not already on the Python Path, in which case
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it will be added.
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For example, if I import /home/foo/my_code.py (and
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/home/foo is not in the python path) as
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"/home/foo/my_code.py|mycode:MyClass.mymethod"
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then /home/foo will be added to the python path and
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the module loaded as normal.
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"""
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filepath, sep, namespace = target.rpartition('|')
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if sep and not filepath:
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raise BadDirectory("Path to file not supplied.")
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module, sep, class_or_function = namespace.rpartition(':')
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if (sep and not module) or (filepath and not module):
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raise MissingModule("Need a module path for %s (%s)" %
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(namespace, target))
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if filepath and filepath not in sys.path:
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if not os.path.isdir(filepath):
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raise BadDirectory("No such directory: '%s'" % filepath)
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sys.path.append(filepath)
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if not class_or_function:
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raise MissingMethodOrFunction("No Method or Function specified in '%s'" % target)
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if module:
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try:
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__import__(module)
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except ImportError as e:
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raise ImportFailed("Failed to import '%s'. Error: %s" % (module, e))
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klass, sep, function = class_or_function.rpartition('.')
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return module, klass, function
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def load(target, source_module=None):
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"""Get the actual implementation of the target."""
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module, klass, function = _get_module(target)
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if not module and source_module:
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module = source_module
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if not module:
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raise MissingModule("No module name supplied or source_module provided.")
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actual_module = sys.modules[module]
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if not klass:
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return getattr(actual_module, function)
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class_object = getattr(actual_module, klass)
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if function:
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return getattr(class_object, function)
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return class_object
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