Class TypeStrVisitor

mypy/types.py:3692–4016

Visitor for pretty-printing types into strings. This is mostly for debugging/testing. Do not preserve original formatting. Notes: - Represent unbound types as Foo? or Foo?[...]. - Represent the NoneType type as None. - Represent Union[x, y] as x | y

class TypeStrVisitor(SyntheticTypeVisitor[str]):
    """Visitor for pretty-printing types into strings.

    This is mostly for debugging/testing.

    Do not preserve original formatting.

    Notes:
     - Represent unbound types as Foo? or Foo?[...].
     - Represent the NoneType type as None.
     - Represent Union[x, y] as x | y
    """

    def __init__(self, id_mapper: IdMapper | None = None, *, options: Options) -> None:
        self.id_mapper = id_mapper
        self.options = options
        self.dotted_aliases: set[TypeAliasType] | None = None

    def visit_unbound_type(self, t: UnboundType, /) -> str:
        s = t.name + "?"
        if t.args:
            s += f"[{self.list_str(t.args)}]"
        return s

    def visit_type_list(self, t: TypeList, /) -> str:
        return f"<TypeList {self.list_str(t.items)}>"

    def visit_callable_argument(self, t: CallableArgument, /) -> str:
        typ = t.typ.accept(self)
        if t.name is None:
            return f"{t.constructor}({typ})"
        else:
            return f"{t.constructor}({typ}, {t.name})"

    def visit_any(self, t: AnyType, /) -> str:
        return "Any"

    def visit_none_type(self, t: NoneType, /) -> str:
        return "None"

    def visit_uninhabited_type(self, t: UninhabitedType, /) -> str:
        return "Never"

    def visit_erased_type(self, t: ErasedType, /) -> str:
        return "<Erased>"

    def visit_deleted_type(self, t: DeletedType, /) -> str:
        if t.source is None:
            return "<Deleted>"
        else:
            return f"<Deleted '{t.source}'>"

    def visit_instance(self, t: Instance, /) -> str:
        fullname = t.type.fullname
        if not self.options.reveal_verbose_types and fullname.startswith("builtins."):
            fullname = t.type.name
        if t.last_known_value and not t.args:
            # Instances with a literal fallback should never be generic. If they are,