From bab532c23f421a537604904254f20b359a1282d2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20St=C3=A4mpfli?= <michael.staempfli@gmail.com>
Date: Tue, 18 Oct 2016 16:52:59 +0200
Subject: [PATCH] Complex topics trigger a Protocol.UndefinedError

---
 lib/pg2pubsub.ex        | 34 ++++++++++++++++++++++++----------
 test/pg2pubsub_test.exs | 13 +++++++++++--
 2 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/lib/pg2pubsub.ex b/lib/pg2pubsub.ex
index 31ecc64..d134acb 100644
--- a/lib/pg2pubsub.ex
+++ b/lib/pg2pubsub.ex
@@ -4,6 +4,11 @@ defmodule Pg2PubSub do
   """
   require Logger
 
+  @typedoc """
+  The name of a topic
+  """
+  @type topic_name :: any
+
   @doc """
   Subscribe to a topic
 
@@ -23,22 +28,26 @@ defmodule Pg2PubSub do
       iex> Pg2PubSub.subscribe("foo")
       {:ok, :already_registered}
 
+      # subscribing to non-string topics
+      iex> Pg2PubSub.subscribe({"job", 14})
+      {:ok, :registered}
+
   """
-  @spec subscribe(String.t) :: term
+  @spec subscribe(topic_name) :: term
   def subscribe(topic) do
-    :ok = Logger.debug "#{inspect self} subscribing to #{topic}..."
+    :ok = Logger.debug "#{inspect self} subscribing to #{inspect topic}..."
     :pg2.create(topic)
     case :pg2.get_members(topic) do
       {:error, error} ->
-        :ok = Logger.error "Publisher failed to get members of topic #{topic}: #{error}"
+        :ok = Logger.error "Publisher failed to get members of topic #{inspect topic}: #{error}"
         {:error, error}
       pids ->
         unless self in pids do
           :pg2.join(topic, self)
-          :ok = Logger.debug "#{inspect self} subscribed to #{topic}"
+          :ok = Logger.debug "#{inspect self} subscribed to #{inspect topic}"
           {:ok, :registered}
       else
-        :ok = Logger.debug "#{inspect self} already subscribed to #{topic}"
+        :ok = Logger.debug "#{inspect self} already subscribed to #{inspect topic}"
         {:ok, :already_registered}
       end
     end
@@ -64,16 +73,21 @@ defmodule Pg2PubSub do
       iex> Pg2PubSub.unsubscribe("foo")
       :ok
 
+      # unsubscribing from non-string topics
+      iex> Pg2PubSub.subscribe({"job", 14})
+      {:ok, :registered}
+      iex> Pg2PubSub.unsubscribe({"job", 14})
+      :ok
   """
-  @spec unsubscribe(String.t) :: term
+  @spec unsubscribe(topic_name) :: term
   def unsubscribe(topic) do
-    :ok = Logger.debug "#{inspect self} unsubscribing from #{topic}..."
+    :ok = Logger.debug "#{inspect self} unsubscribing from #{inspect topic}..."
     case :pg2.leave(topic, self) do
       {:error, {:no_such_group, _topic}} ->
-        :ok = Logger.warn "no subscribers for topic #{topic}"
+        :ok = Logger.warn "no subscribers for topic #{inspect topic}"
         :ok
       :ok ->
-        :ok = Logger.debug "#{inspect self} unsubscribed from #{topic}"
+        :ok = Logger.debug "#{inspect self} unsubscribed from #{inspect topic}"
         :ok
     end
   end
@@ -97,7 +111,7 @@ defmodule Pg2PubSub do
       "bar"
 
   """
-  @spec publish(String.t, any) :: :ok
+  @spec publish(topic_name, any) :: :ok
   def publish(topic, msg) do
     case :pg2.get_members(topic) do
       {:error, err} ->
diff --git a/test/pg2pubsub_test.exs b/test/pg2pubsub_test.exs
index e89b921..c60192b 100644
--- a/test/pg2pubsub_test.exs
+++ b/test/pg2pubsub_test.exs
@@ -4,7 +4,7 @@ defmodule Pg2PubSubTest do
 
   setup do
     :pg2.which_groups
-    |> Enum.map fn (x) -> :pg2.delete(x) end
+    |> Enum.map(fn (x) -> :pg2.delete(x) end)
     :ok
   end
 
@@ -42,4 +42,13 @@ defmodule Pg2PubSubTest do
     assert_receive :foo
     refute_receive :foo # check only received once
   end
-end
\ No newline at end of file
+
+  test "supports more complex topics than just strings" do
+    Pg2PubSub.subscribe({:context, "bar"})
+
+    Pg2PubSub.publish({:context, "bar"}, :bar)
+    Pg2PubSub.unsubscribe({:context, "bar"})
+
+    assert_receive :bar
+  end
+end