sequence_server.ex

defmodule Sequence.Server do

  use GenServer.Behaviour

  # External API
  def start_link(current_number) do
    :gen_server.start_link({ :local, :sequence }, __MODULE__, current_number, [])
  end

  def next_number do
    :gen_server.call :sequence, :next_number
  end

  def increment_number(delta) do
    :gen_server.cast :sequence, {:increment_number, delta}
  end

  # gen_server callbacks
  def init(current_number)  when is_number(current_number) do
    { :ok, current_number }
  end

  def handle_call(:next_number, _from, current_number) do
    { :reply, current_number, current_number+1 }
  end

  def handle_cast({:increment_number, delta}, current_number) do
    { :noreply, current_number + delta}
  end

end