Ignoring in handle_info/2 is OK. Really?

Questions / Help
1

Hi! The guides suggest a clause

def handle_info(_msg, state) do
  {:noreply, state}
end

to handle unexpected messages received by GenServer. But such ignoring can result in ignoring developers’ errors. So, I guess, there can be reasons to crash early on unexpected messages. Or - at least - log them. But not ignoring.

Please, show me where I’m wrong :slight_smile:

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2

I agree with your point. I would expect to at least log unexpected messages. I suspect the guides’ point is to get people started with minimal tangents. OTP has certain “housekeeping” sorts of messages that come into handle_info that doesn’t make a lot of sense to explain to someone brand new to the framework, and that in many cases you really should just ignore, but I agree with the idea to log them. That way you’ll be aware of them and can start seeing what they mean when you run across them.

1 Like
3

Thanks for information! So, to be pedant :), we want to separate “housekeeping” messages from really not expected. Don’t we?

4

Btw, Elixir v1.4 will be moving towards to logging in such cases.

3 Likes
5

What is “such cases” at the context? All housekeeping messages, all unmatched messages, difference between the last and the former, or… what? :slight_smile:

6

Sorry. The default implementation for handle_info, which is the catch all
clause for unhandled messages will now log. If you provide your own
clauses, you need your own catch all and your own log though.

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7

Aha, I see, thanks for the clarification! So, the default case will force a developer to notice “something else is happening”, and it is great. It is a motivation to recognize the reality…