Class Unicode

traitlets/traitlets.py:2910–2983

A trait for unicode strings.

class Unicode(TraitType[G, S]):
    """A trait for unicode strings."""

    default_value = ""
    info_text = "a unicode string"

    if t.TYPE_CHECKING:

        @t.overload
        def __init__(
            self: Unicode[str, str | bytes],
            default_value: str | Sentinel = ...,
            allow_none: Literal[False] = ...,
            read_only: bool | None = ...,
            help: str | None = ...,
            config: t.Any = ...,
            **kwargs: t.Any,
        ) -> None:
            ...

        @t.overload
        def __init__(
            self: Unicode[str | None, str | bytes | None],
            default_value: str | Sentinel | None = ...,
            allow_none: Literal[True] = ...,
            read_only: bool | None = ...,
            help: str | None = ...,
            config: t.Any = ...,
            **kwargs: t.Any,
        ) -> None:
            ...

        def __init__(
            self: Unicode[str | None, str | bytes | None],
            default_value: str | Sentinel | None = ...,
            allow_none: bool = ...,
            read_only: bool | None = ...,
            help: str | None = ...,
            config: t.Any = ...,
            **kwargs: t.Any,
        ) -> None:
            ...

    def validate(self, obj: t.Any, value: t.Any) -> G:
        if isinstance(value, str):
            return value  # type:ignore[return-value]
        if isinstance(value, bytes):
            try:
                return value.decode("ascii", "strict")  # type:ignore[return-value]
            except UnicodeDecodeError as e:
                msg = "Could not decode {!r} for unicode trait '{}' of {} instance."
                raise TraitError(msg.format(value, self.name, class_of(obj))) from e
        self.error(obj, value)

    def from_string(self, s: str) -> G:
        if self.allow_none and s == "None":
            return None  # type:ignore[return-value]
        s = os.path.expanduser(s)