The result of mentioned post was an issue:
with José Valim solution:
Currently when you write this code:
defmodule Example do
@doc "foo"
@callback foo() :: :ok
end
defmodule Sample do
@behaviour Example
def foo, do: :ok
end
You have:
$ iex -S mix
Erlang/OTP 24 [erts-12.3.1] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [jit]
Interactive Elixir (1.13.3) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> b Example.foo
@callback foo() :: :ok
foo
iex(2)> h Sample.foo
def foo()
Sample.foo/0 has no docs but is a callback for behaviour Example. Showing
callback docs instead.
@callback foo() :: :ok
foo
ex_doc shows:
Callback implementation for
Example.foo/0
with a link to callback documentation.
Having in mind above you do not need to write a spec. However if you write any @doc to your implementation then you need to note c:Module.callback/arity, so for example in ex_doc you can quickly navigate to said callback to see it’s @spec. Also modern editors are able to show same docs in popup. Therefore you do not need to write @spec on yourself.
However there is something weird if you add @impl true or @imple Example to Sample.foo/0 implementation. There are no documentation both in iex and ex_doc, so maybe it at least was intended. It’s worth to open an issue for that.
