Hi When I use @behaviour and @callback, the functions are defined. I guess that I do not need to use @spec for the implementation of the @impl functions as well? Will Dialyzer sort this out as well? Br Patrik

You don’t need them as Dialyzer will give a callback does not match spec error, but please include them anyway. As a reader I do not want to have to jump to the behaviour definition to find out what the arguments are. In that vein if you include a using macro where you define default callbacks that …

[image] asummers: You don’t need them as Dialyzer will give a callback does not match spec error, but please include them anyway. As a reader I do not want to have to jump to the behaviour definition to find out what the arguments are. In that vein if you include a using macro where you define d…

I’m very unclear which part of my suggestion you’re taking umbrage with. Can you give an example of what you’re talking about?

[image] asummers: I’m very unclear which part of my suggestion you’re taking umbrage with. Can you give an example of what you’re talking about? Sure, here is your changed code: defmodule MyBehaviour do @callback foo() :: :ok end defmodule MyImpl do @behaviour MyBehaviour @doc delega…

I wasn’t suggesting to use a macro. Simply saying that if you do have a macro and the function is overridable to elide the spec in the macro (as they do in e.g. GenServer but do NOT elide in HTTPoison). I don’t think they’re incompatible, unless I’m misunderstanding something. This thread is about @…

[image] asummers: This thread is about @spec not @doc . Yes, it is - look that delegated callback/function have also its specification (not only documentation - I did not even added documentation to your behaviour code). As said if there is really no need to write macro then we should avoid …

Again, I’m not advocating for the macro, at all, in any way shape or form. I agree in this case it’s not needed. I’m contrasting the approaches taken between GenServer and HTTPoison.Base. elixir-lang/elixir/blob/master/lib/elixir/lib/gen_server.ex#L760 id: __MODULE__, start: {__MO…

GenServer is not good example here is it’s most probably intended to not add @doc and @spec to those functions. Anyway I can see what you are talking about. For sure adding @doc false when you really expect documentation is really bad, but @doc delegate_to is still ok here More … for this use case …

Hi Wow, thanks for all comments! Did not know that this would stir up this many opinions. :slight_smile: A see your point @asummers , but since this is not a public library (“only” used within our company), I prefer that the implementers spend the extra time to go into the definition of the behavio…

[image] paseg: Dialyzer signals this is ok For sure if you have different @spec for specific implementation than @callback then you should use @spec. It’s important to let other knows that you will not meet exactly all cases expected by @behaviour. Otherwise I suggest delegating to callback d…

@behaviour, @callback and @spec

Questions & Help Questions

Eiji August 30, 2021, 5:11pm 13

Looks like a bug. When @callback is used delegate_to option seems to be ignored …

Should using @impl true cause docs to show the callback spec?