Event field types include None but (maybe) shouldn't

[timoffex]

With the new 4.2.0 release that adds the py.typed marker, mypy is reporting that my Event handling code should be ready for None values. For instance,

if isinstance(event, h2.events.RequestReceived):
    stream = HTTP2StreamHandler(
        self._state,
        event.stream_id, # mypy: incompatible type "int | None"; expected "int"
        event.headers,   # mypy: incompatible type "list[HeaderTuple] | None"; expected "Iterable[HeaderTuple]"
    )

I can expect these fields to always be set, right? I could add assert statements like this:

if isinstance(event, h2.events.RequestReceived):
    assert event.stream_id is not None
    assert event.headers is not None
    stream = HTTP2StreamHandler(
        self._state,
        event.stream_id,
        event.headers,
    )

But it's clunky to make users do this.

I see that Event objects are constructed incrementally, so their fields can be None temporarily in h2 code, but I wish the types could reflect what I should expect as a user. What would you think of something like this?

class RequestReceived(Event):
    stream_id: int
    headers: list[HeaderTuple]

    def __init__(self) -> None:
        self.stream_ended: StreamEnded | None = None
        self.priority_updated: PriorityUpdated | None = None

It would work as long as h2 itself does not access stream_id / headers before setting them.

[Kriechi]

This should now already be addressed in #1296 - please review and provide feedback!

[timoffex]

Wonderful, I should have known you guys were already a step ahead! It looks like the PR fixes all the events I was using, so I will close the issue.