*Org Src refile.org[ elixir ]*.ex

defmodule SimpleBus do
  def init do
    {:ok, _} = Registry.start_link(:duplicate, __MODULE__)
  end

  def register_handler(module) do
    Registry.register(__MODULE__, :event, module)
  end

  def emit(event_name, args) do
    {:ok, agent} = Agent.start_link(fn -> nil end)

    Registry.dispatch __MODULE__, :event, fn entries ->
      result = for {_pid, module} <- entries do
        {module, module.handle_event(event_name, args)}
      end

      Agent.update(agent, fn _ -> result end)
    end

    results = Agent.get(agent, & &1)
    Agent.stop(agent)

    for {handler, result} <- results, result != :ignored do
      {handler, result}
    end
  end
end

defmodule Handler do
  defmacro __using__(_) do
    quote do
      @before_compile Handler
    end
  end

  defmacro __before_compile__(_) do
    quote do
      def handle_event(_, _), do: :ignored
    end
  end
end

defmodule Handler1 do
  use Handler

  def handle_event(:tuff, lek), do: IO.inspect lek
end

SimpleBus.init

SimpleBus.emit(:tuff, "leklek")
SimpleBus.emit(:LOL, nil)

SimpleBus.register_handler(Handler1)

SimpleBus.emit(:tuff, "leklek")
SimpleBus.emit(:LOL, nil)