Implement EredisSub.Handler behaviour

lib/eredis_sub/handler.ex

@@ -0,0 +1,12 @@
+defmodule EredisSub.Handler do
+  @moduledoc """
+  Behaviour for handling messages received from Redis.
+  """
+
+  @doc """
+  Handles a message received from Redis.
+  Receives a binary message and a metadata that can be customized upon subscription.
+  Return value is ignored.
+  """
+  @callback handle(binary, term) :: term
+end