defmodule Modular.Mutability do
  @moduledoc """
  Provides command/query annotations for functions within area contracts.

  ## Examples

      defmodule Invoicing do
        use Modular.Mutability

        @command true
        def create_user, do: :error

        @query true
        def get_users, do: []
      end

  """

  defmacro __using__(_) do
    quote do
      require unquote(__MODULE__)

      @before_compile unquote(__MODULE__)
    end
  end

  defmacro __before_compile__(_env) do
    quote do
      Module.delete_attribute(__MODULE__, :query)
      Module.delete_attribute(__MODULE__, :command)
    end
  end
end