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- # Use of this source code is governed by a BSD-style
- # license that can be found in the LICENSE file.
- # Copyright 2019 The OSArchiver Authors. All rights reserved.
- """
- Common functions of osarchiver
- """
- from importlib import import_module
- def backend_factory(*args, backend='db', module=None, subclass=None, **kwargs):
- """
- This factory function rule is to return the backend instances
- It raises an exception on import or attribute error or unavailable backend
- """
- try:
- class_name = backend.capitalize()
- backend_module = import_module(module + '.' + backend)
- backend_class = getattr(backend_module, class_name)
- instance = backend_class(*args, **kwargs)
- except (AttributeError, ImportError):
- raise ImportError("{} is not part of our backend"
- " collection!".format(backend))
- else:
- if not issubclass(backend_class, subclass):
- raise ImportError("Unsupported '{}' destination"
- " backend".format(backend))
- return instance
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