58 lines
1.8 KiB
Python
58 lines
1.8 KiB
Python
"""Catalog module."""
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from .providers import Provider
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class AbstractCatalog(object):
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"""Abstract object provides catalog."""
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__slots__ = ('__used_providers__',)
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def __init__(self, *used_providers):
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"""Initializer."""
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self.__used_providers__ = set(used_providers)
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def __getattribute__(self, item):
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"""Return providers."""
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attribute = super(AbstractCatalog, self).__getattribute__(item)
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if item in ('__used_providers__',):
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return attribute
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if attribute not in self.__used_providers__:
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raise AttributeError('Provider \'{}\' is not listed in '
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'dependencies'.format(item))
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return attribute
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@classmethod
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def __all_providers__(cls, provider_type=Provider):
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"""Return set of all class providers."""
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providers = set()
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for attr_name in set(dir(cls)) - set(dir(AbstractCatalog)):
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provider = getattr(cls, attr_name)
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if not isinstance(provider, provider_type):
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continue
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providers.add((attr_name, provider))
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return providers
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@classmethod
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def __override___(cls, overriding):
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"""
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Override current catalog providers by overriding catalog providers.
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:param overriding: AbstractCatalog
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"""
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overridden = overriding.__all_providers__() - cls.__all_providers__()
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for name, provider in overridden:
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overridden_provider = getattr(cls, name)
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overridden_provider.__override__(provider)
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def overrides(catalog):
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"""Catalog overriding decorator."""
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def decorator(overriding_catalog):
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"""Overriding decorator."""
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catalog.__override___(overriding_catalog)
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return overriding_catalog
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return decorator
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