Multi alias use is not detected

[aweiker]

Elixir 1.2 added support for multi use aliases. Credo should pick this up and not warn on missing aliases.

Here is an example that should be allowed and not have any warnings.

defmodule Sample.App do
  @moduledoc false

  alias Sample.App.{One, Two}

  def foo do
    {One.one, Two.two}
  end
end

defmodule Sample.App.One do
  @moduledoc false
  def one, do: "One"
end

defmodule Sample.App.Two do
  @moduledoc false
  def two, do: "Two"
end

However, this will give the following messages

  Software Design
┃
┃ [D] ↓ Nested modules could be aliased at the top of the invoking module.
┃       lib/sample.ex:7:22 (Sample.foo)
┃ [D] ↓ Nested modules could be aliased at the top of the invoking module.
┃       lib/sample.ex:7:6 (Sample.foo)

Please report incorrect results: https://github.com/rrrene/credo/issues

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6 mods/funs, found 2 software design suggestions.

[rrrene]

Hi Aaron,

maybe you mistyped your example, but that is not how you use aliasing. An alias is used to reference a given module by another (shorter) name, which is by default the last part of the module atom. Your Sample module should therefore read:

defmodule Sample do
  @moduledoc false

  alias Sample.{One, Two}

  def foo do
    {One.one, Two.two}      # <----
  end
end

Was this a typo in your example or did I misinterpret the report? In any case, thanks for reporting! 👍

[aweiker]

Yes, you are correct. I messed up the sample.

I corrected the sample that way it's obvious.

Also, what I just discovered while updating it is that this works Sample.One and Sample.Two but when it is Sample.App.One and Sample.App.Two it does not.

[aweiker]

Doing some more digging into it and it appears that this may be the preferred syntax and it currently does get through the current checks.

defmodule Sample.App do
  @moduledoc false

  alias Sample.{App.One, App.Two}  # <----

  def foo do
    {One.one, Two.two}
  end
end

[rrrene]

v0.3.8 contains a fix for this. Would you mind test-driving it? 😁

[aweiker]

Looks good.