AtAt: The pinnacle of Elixir MetaProgramming.

the_pinnacle_of_elixir_metaprogramming.exs

defmodule AtAt do
  defmacro __using__(_opts) do
    quote do
      import AtAt
      import Kernel, except: [@: 1]
    end
  end


  defmacro @(val) do
    case val do
      {:@, _, [{name, context, args}]} ->
        {count, inner} = count_ats({name, context, args}, 2)
        quote bind_quoted: [count: count, inner: inner, escaped_inner: Macro.escape(inner)] do
          IO.inspect("Wow! Running #{Macro.to_string(escaped_inner)} with #{count} ats!")
          inner
        end
      _ -> quote do Kernel.@(unquote(val)) end
    end
  end

  defp count_ats({:@, _, [{name, context, args}]}, accum) do
    count_ats({name, context, args}, accum + 1)
  end
  defp count_ats(other, accum) do
    {accum, other}
  end
end

Usage instructions:

iex> use AtAt
iex> @@@@@@@@@@@@@@@@@@@@@@@self()
"Wow! Running self() with 23 ats!"
#PID<0.85.0>