Dynamically add module functions in __using__ macro

Questions & Help Questions
1

I have a bunch of functions in a module, that I’d like to dynamically add to a __using__ macro:

defmodule A do
  defmacro __using__(_opts) do
    quote do
      # Dynamically add 
      # def foo(), do: "Foo"
      # and any other functions.
    end
  end

  def foo(), do: "Foo"
end

My goal is to have the functions accessible on the original module, inject them into the module that’s using it via use and make them overridable:

I’m just starting with metaprogramming so I’d appreciate any solutions or pointers in the right direction. Thanks!