i_wish_this_was_ruby.exs

defmodule MyApp.Delegator do
  defmacro __using__(opts) do
    quote do
      def unquote(:"$handle_undefined_function")(name, args) do
        apply(Keyword.get(unquote(opts), :target), name, args)
      end
    end
  end
end

defmodule MyApp.ACMECO do
  def hello(), do: "hello"
  def goodbye(), do: "goodbye"
end

defmodule MyApp.ACMECO.Staging do
  use MyApp.Delegator, target: MyApp.ACMECO

  def hello(), do: "HELLO YALL"
end

IO.inspect(MyApp.ACMECO.Staging.hello())
IO.inspect(MyApp.ACMECO.Staging.goodbye())