Dynamically Loading a Module in Elixir

Elixir way of keeping code clear and reusable is creating modules and importing them when needed. However import method is easy to use for static module names, it requires more afford to load dynamically assigned modules.

Suppose that you need to import, require a module using configuration. Then you can read the configuration by:

Application.get_env(:my_app, :module_ref)

And import, require like:

import Application.get_env(:my_app, :module_ref)
# or
require Application.get_env(:my_app, :module_ref)

But it wont work! An error will raise like:

invalid argument for import, expected a compile time atom or alias, got: Application.get_env(:my_app, :module_ref)

In order to ‘import’ or ‘require’ a module dynamically you need to create an ‘importer module’ like and import using macros:

defmodule MyApp.Importer do
  @moduledoc """
  Dynamically import configured module into your module.
  ### Examples
      defmodule SomeModule do
        ...
        use MyApp.Importer
        ...
        def xyz do
          ...
          some_func_from_ref_module()
          ...
        end
      end
  """
  defmacro __using__(_) do
    quote do
      import unquote(Application.get_env(:my_app, :module_ref))
    end
  end
end
config :my_app,
  module_ref: MyApp.SomeModule

When you need some dynamics in your code base, look into macros. Most probably solution will underly on quote and unquote tags.