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https://github.com/ets-labs/python-dependency-injector.git
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76 lines
2.2 KiB
Python
76 lines
2.2 KiB
Python
"""Catalog module."""
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import six
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from .errors import Error
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from .utils import is_provider
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class CatalogMetaClass(type):
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"""Providers catalog meta class."""
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def __new__(mcs, class_name, bases, attributes):
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"""Meta class factory."""
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providers = dict()
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new_attributes = dict()
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for name, value in six.iteritems(attributes):
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if is_provider(value):
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providers[name] = value
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new_attributes[name] = value
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cls = type.__new__(mcs, class_name, bases, new_attributes)
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cls.providers = cls.providers.copy()
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cls.providers.update(providers)
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return cls
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@six.add_metaclass(CatalogMetaClass)
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class AbstractCatalog(object):
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"""Abstract providers catalog."""
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providers = dict()
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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 ('providers', 'used_providers',):
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return attribute
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if attribute not in self.used_providers:
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raise Error('Provider \'{0}\' '.format(item) +
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'is not listed in dependencies')
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return attribute
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@classmethod
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def filter(cls, provider_type):
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"""Return dict of providers, that are instance of provided type."""
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return dict((name, provider)
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for name, provider in six.iteritems(cls.providers)
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if isinstance(provider, provider_type))
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@classmethod
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def override(cls, overriding):
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"""Override current catalog providers by overriding catalog providers.
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:type overriding: AbstractCatalog
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"""
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for name, provider in six.iteritems(overriding.providers):
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cls.providers[name].override(provider)
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def override(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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