Class NoneType

mypy/types.py:1429–1467

The type of 'None'. This type can be written by users as 'None'.

class NoneType(ProperType):
    """The type of 'None'.

    This type can be written by users as 'None'.
    """

    __slots__ = ()

    def __init__(self, line: int = -1, column: int = -1) -> None:
        super().__init__(line, column)

    def can_be_true_default(self) -> bool:
        return False

    def __hash__(self) -> int:
        return hash(NoneType)

    def __eq__(self, other: object) -> bool:
        return isinstance(other, NoneType)

    def accept(self, visitor: TypeVisitor[T]) -> T:
        return visitor.visit_none_type(self)

    def serialize(self) -> JsonDict:
        return {".class": "NoneType"}

    @classmethod
    def deserialize(cls, data: JsonDict) -> NoneType:
        assert data[".class"] == "NoneType"
        return NoneType()

    def write(self, data: WriteBuffer) -> None:
        write_tag(data, NONE_TYPE)
        write_tag(data, END_TAG)

    @classmethod
    def read(cls, data: ReadBuffer) -> NoneType:
        assert read_tag(data) == END_TAG
        return NoneType()


# NoneType used to be called NoneTyp so to avoid needlessly breaking