Class RawExpressionType

mypy/types.py:3106–3186

A synthetic type representing some arbitrary expression that does not cleanly translate into a type. This synthetic type is only used at the beginning stages of semantic analysis and should be completely removing during the process for mapping UnboundTypes to actual types: we either

class RawExpressionType(ProperType):
    """A synthetic type representing some arbitrary expression that does not cleanly
    translate into a type.

    This synthetic type is only used at the beginning stages of semantic analysis
    and should be completely removing during the process for mapping UnboundTypes to
    actual types: we either turn it into a LiteralType or an AnyType.

    For example, suppose `Foo[1]` is initially represented as the following:

        UnboundType(
            name='Foo',
            args=[
                RawExpressionType(value=1, base_type_name='builtins.int'),
            ],
        )

    As we perform semantic analysis, this type will transform into one of two
    possible forms.

    If 'Foo' was an alias for 'Literal' all along, this type is transformed into:

        LiteralType(value=1, fallback=int_instance_here)

    Alternatively, if 'Foo' is an unrelated class, we report an error and instead
    produce something like this:

        Instance(type=typeinfo_for_foo, args=[AnyType(TypeOfAny.from_error))

    If the "note" field is not None, the provided note will be reported alongside the
    error at this point.

    Note: if "literal_value" is None, that means this object is representing some
    expression that cannot possibly be a parameter of Literal[...]. For example,
    "Foo[3j]" would be represented as:

        UnboundType(
            name='Foo',
            args=[
                RawExpressionType(value=None, base_type_name='builtins.complex'),
            ],
        )
    """

    __slots__ = ("literal_value", "base_type_name", "note")

    def __init__(
        self,
        literal_value: LiteralValue | None,
        base_type_name: str,
        line: int = -1,
        column: int = -1,
        note: str | None = None,
    ) -> None:
        super().__init__(line, column)
        self.literal_value = literal_value
        self.base_type_name = base_type_name
        self.note = note