In my opinion it doesn’t really belong to start_link. It’s a behaviour for the init/1 callback, as you can see in the GenServer module, where it’s even mentioned in the documentation text.
LostKobrakai
0
sasajuric
Author of Elixir In Action
I believe you actually got it right initially. It seems that Supervisor.start_link/2 can’t return :ignore (unless I’m missing some nuance, since I didn’t bother to read the code of Supervisor). Even the docs for start_link/2 don’t mention it.
You can consider making a PR which would tighten the specification for start_link/2.
1
LostKobrakai
It surely can if at least for the Supervisor.start_link/3 version, but skipping the optional options, which are the 3rd parameter.
3
peerreynders
It is this type of thing why I would give priority to
[Erlang] Designing for Scalability with Erlang/OTP (O'Reilly)
over
The Little Elixir & OTP Guidebook (Manning)
This goes back to the Erlang documentation:
1
sasajuric
Author of Elixir In Action
Ah, good point! I forgot about the optional options thing for start_link/3. Yeah, in that case, :ignore is indeed a valid return value.
1