Background I have a module that is a GenStage. I am trying to make this module dyalizer compliant but I am not sure if I am going overboard with @spec. Code Imagine we have the following code: @impl GenStage def init(args) do {:producer_consumer, nil} end This code is the init callback of a Gen…

If the spec is a subset of what is described per the callback, then it doesn’t clash. I’m not sure though how dialyzer looks at it, also, as the interface is defined from the outside world, I’d not try to re(de)fine the spec.

From the documentation it seems as if that additionally to erroring when impls are missing or no callback that fits the impl, only @doc false is implied on @impl. Though, in general, whether you have @impl or not, dialyzer will check you function against the @callback type when you implement a call…

But which way would you recommend? Would the @spec clash?

You can provide a typespec for behaviour callback functions. If you do so, and some arg or the return type in your spec is not a subtype of the callback spec, dialyzer will emit a corresponding warning. The same will happen if the types inferred from the callback code do not match spec types. So e.…

[image] sasajuric: So far, I didn’t got into a habit of writing specs for callbacks, but I’ve been toying with this idea for some time. I think it would help documenting expected callback args, and might help catching some errors. I’ve been toying with this idea as well, but I left it because…

Elixir Programming Language Forum

Does dyalizer need @spec when a function has @impl?

Questions & Help Questions

Fl4m3Ph03n1x January 15, 2020, 3:30pm 5

I see. Better play it safe!