Class Option

src/py/reactpy/reactpy/_option.py:14–137

An option that can be set using an environment variable of the same name

class Option(Generic[_O]):
    """An option that can be set using an environment variable of the same name"""

    def __init__(
        self,
        name: str,
        default: _O = UNDEFINED,
        mutable: bool = True,
        parent: Option[_O] | None = None,
        validator: Callable[[Any], _O] = lambda x: cast(_O, x),
    ) -> None:
        self._name = name
        self._mutable = mutable
        self._validator = validator
        self._subscribers: list[Callable[[_O], None]] = []

        if name in os.environ:
            self._current = validator(os.environ[name])

        if parent is not None:
            if not (parent.mutable and self.mutable):
                raise TypeError("Parent and child options must be mutable")
            self._default = parent.default
            parent.subscribe(self.set_current)
        elif default is not UNDEFINED:
            self._default = default
        else:
            raise TypeError("Must specify either a default or a parent option")

        logger.debug(f"{self._name}={self.current}")

    @property
    def name(self) -> str:
        """The name of this option (used to load environment variables)"""
        return self._name

    @property
    def mutable(self) -> bool:
        """Whether this option can be modified after being loaded"""
        return self._mutable

    @property
    def default(self) -> _O:
        """This option's default value"""
        return self._default

    @property
    def current(self) -> _O:
        try:
            return self._current
        except AttributeError:
            return self._default

    @current.setter
    def current(self, new: _O) -> None:
        self.set_current(new)

    @current.deleter