overrides in elixir

overrides.exs

defmodule Foo do
	defmacro __using__(_) do
		quote do
			def foo() do
				IO.puts "Foo"
			end
			defoverridable [foo: 0]
		end
	end
end

defmodule Bar do
	use Foo
	def foo() do
		IO.puts "Bar start"
		super()
		IO.puts "Bar end"
	end
end

IO.puts "\nTesting Bar"
Bar.foo
# Bar start
# Foo
# Bar end

defmodule Baz do
	defmacro __using__(_) do
		quote do
			use Foo
			def foo() do
				IO.puts "Baz start"
				super()
				IO.puts "Baz end"
			end
			defoverridable [foo: 0]
		end
	end
end

defmodule Qux do
	use Baz
	def foo() do
		IO.puts "Qux start"
		super()
		IO.puts "Qux end"
	end
end

IO.puts "\nTesting Qux"
Qux.foo
# Qux start
# Baz start
# Foo
# Baz end
# Qux end

defmodule Test do
	use Baz
	use Foo
end

IO.puts "\nTesting Test"
Test.foo
# Foo