django-stubs 4.2.1 gives transaction.on_commit a more accurate type
annotation, but this exposed that mypy can’t handle the lambda default
parameters that we use to recapture loop variables such as
for stream_id in public_stream_ids:
peer_user_ids = …
event = …
transaction.on_commit(
lambda event=event, peer_user_ids=peer_user_ids: send_event(
realm, event, peer_user_ids
)
)
https://github.com/python/mypy/issues/15459
A workaround that mypy accepts is
transaction.on_commit(
(
lambda event, peer_user_ids: lambda: send_event(
realm, event, peer_user_ids
)
)(event, peer_user_ids)
)
But that’s kind of ugly and potentially error-prone, so let’s make a
helper function for this very common pattern.
send_event_on_commit(realm, event, peer_user_ids)
Signed-off-by: Anders Kaseorg <anders@zulip.com>
Anders Kaseorg