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64 lines
1.9 KiB
Python
64 lines
1.9 KiB
Python
import six
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from ..utils.is_base_type import is_base_type
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from ..utils.trim_docstring import trim_docstring
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from .abstracttype import AbstractTypeMeta
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from .field import Field
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from .options import Options
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from .utils import get_base_fields, merge, yank_fields_from_attrs
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class InterfaceMeta(AbstractTypeMeta):
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def __new__(cls, name, bases, attrs):
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# Also ensure initialization is only performed for subclasses of
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# Interface
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if not is_base_type(bases, InterfaceMeta):
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return type.__new__(cls, name, bases, attrs)
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options = Options(
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attrs.pop('Meta', None),
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name=name,
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description=trim_docstring(attrs.get('__doc__')),
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local_fields=None,
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)
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options.base_fields = get_base_fields(bases, _as=Field)
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if not options.local_fields:
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options.local_fields = yank_fields_from_attrs(attrs, _as=Field)
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options.fields = merge(
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options.base_fields,
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options.local_fields
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)
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return type.__new__(cls, name, bases, dict(attrs, _meta=options))
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def __str__(cls): # noqa: N802
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return cls._meta.name
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class Interface(six.with_metaclass(InterfaceMeta)):
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'''
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Interface Type Definition
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When a field can return one of a heterogeneous set of types, a Interface type
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is used to describe what types are possible, what fields are in common across
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all types, as well as a function to determine which type is actually used
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when the field is resolved.
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'''
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@classmethod
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def resolve_type(cls, instance, context, info):
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from .objecttype import ObjectType
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if isinstance(instance, ObjectType):
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return type(instance)
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def __init__(self, *args, **kwargs):
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raise Exception("An Interface cannot be intitialized")
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@classmethod
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def implements(cls, objecttype):
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pass
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