dataevent.py

from asyncio import Event
from typing import TypeVar, Generic


T = TypeVar("T")


class Unset:
    pass


class DataEvent(Event, Generic[T]):
    def __init__(self, *args, **kwargs) -> None:
        super().__init__(*args, **kwargs)

        self.data: T | Unset = Unset()

    async def wait(self) -> T:
        await super().wait()

        if isinstance(self.data, Unset):
            raise ValueError("DataEvent data is not set at end of event wait.")

        return self.data

    def set(self, data: T) -> None:
        self.data = data