types.py 文件源码

def __new__(cls, name, bases, attrs):
        # Also ensure initialization is only performed for subclasses of Model
        # (excluding Model class itself).
        if not is_base_type(bases, PynamoObjectTypeMeta):
            return type.__new__(cls, name, bases, attrs)

        options = Options(
            attrs.pop('Meta', None),
            name=name,
            description=attrs.pop('__doc__', None),
            model=None,
            local_fields=None,
            only_fields=(),
            exclude_fields=(),
            id='id',
            interfaces=(),
            registry=None
        )

        if not options.registry:
            options.registry = get_global_registry()
        assert isinstance(options.registry, Registry), (
            'The attribute registry in {}.Meta needs to be an'
            ' instance of Registry, received "{}".'
        ).format(name, options.registry)

        assert (inspect.isclass(options.model) and issubclass(options.model, Model)), (
            'You need to pass a valid PynamoDB Model in '
            '{}.Meta, received "{}".'
        ).format(name, options.model)

        cls = ObjectTypeMeta.__new__(cls, name, bases, dict(attrs, _meta=options))

        options.registry.register(cls)

        options.pynamo_fields = yank_fields_from_attrs(
            construct_fields(options),
            _as=Field,
        )
        options.fields = merge(
            options.interface_fields,
            options.pynamo_fields,
            options.base_fields,
            options.local_fields
        )

        return cls