lib/xapi/env.ex

defmodule Xmeta.Xapi.Env do
  @doc """
  atom_type =  :api, :router, :site
  """
  def put_module(module, atom_type) do
    unless Application.get_application(module) do
      mods = Application.get_env(:xmeta, atom_type)
      mods = if mods, do: mods, else: []

      if module not in mods do
        Application.put_env(:xmeta, atom_type, mods ++ [module])
      end
    end
  end
end