Consumer event list in handle_events return #36
Description
When reading the recent blog post I got confused by:
# We are a consumer, so we never emit events.
{:noreply, [], sleeping_time}
If a consumer can never emit events then why am I required to return a list of events for it to not emit?
Of course if I don't make this list of events an empty list I'll get an error:
defp dispatch_events(events, %{type: :consumer} = stage) do
:error_logger.error_msg('GenStage consumer ~p cannot dispatch events (an empty list must be returned): ~p~n', [name(), events])
stage
end
But then if it knows the return value is always [] why do I have to tell it?
I'd argue that handle_events have the type:
{:noreply, new_state} |
{:noreply, new_state, :hibernate} |
{:noreply, [event], new_state} |
{:noreply, [event], new_state, :hibernate} |
{:stop, reason, new_state} when new_state: term, reason: term, event: term
And when handling mod.handle_events match on the type of process currently running since only consumer should be using the return type with no list of events.
Now I also notice that :noreply appears to be superfluous. You can never reply, so why say :noreply at all? It is an odd way to differentiate from :stop, so maybe unnecessary?