Add :callback to opts and use Supervisor.init/2

* Adds a :callback to opts which takes a function capture
  or an MFA. The function is called when the :ets table
	is created and the supervisor is up.
* Uses Supervisor.init/2 to avoid deprecation messages
* Updates Elixir version to 1.5 which is when Supervisor.init/2
  was introduced
* Adds tests for the :callback option

README.md

@@ -11,7 +11,7 @@ Eternal is available on [Hex](https://hex.pm/). You can install the package via:
 
     ```elixir
     def deps do
-      [{:eternal, "~> 1.2"}]
+      [{:eternal, "~> 1.3"}]
     end
     ```
 
@@ -103,6 +103,17 @@ defmodule MyApplication.OneForAllSupervisor do
 end
 ```
 
+## Application callback
+
+If your application would like to be informed when the supervisor is operation and the :ets table is created you may pass the option `:callback` to the `Eternal.start_link/3` and `Eternal.start/3` functions. The callback is a function specification of the form either `{Module, function, [args]}` or a function capture. For example:
+```elixir
+# The parameters pid and table are passed to the callback
+iex> Eternal.start_link MyTable, [], callback: fn pid, table -> callback_fun(pid, table) end
+
+# The parameters pid and table are pre-prended to args
+iex> Eternal.start_link Eternal, [], callback: {MyModule, :callback_fun, []}, quiet: true
+```
+
 ## Contributions
 
 If you feel something can be improved, or have any questions about certain behaviours or pieces of implementation, please feel free to file an issue. Proposed changes should be taken to issues before any PRs to avoid wasting time on code which might not be merged upstream.

lib/eternal.ex

@@ -150,7 +150,24 @@ defmodule Eternal do
       Priv.heir(table, pid2)
       Priv.gift(table, pid1)
 
+      maybe_process_callback(opts[:callback], pid, table)
       res
     end
   end
+
+  # Callback function when the :ets table
+  # is created and the supervisor process
+  # is up and running.
+  defp maybe_process_callback(nil, _pid, _table) do
+    nil
+  end
+
+  defp maybe_process_callback(fun, pid, table) when is_function(fun, 2) do
+    fun.(pid, table)
+  end
+
+  defp maybe_process_callback({module, function, args}, pid, table)
+      when is_mfa(module, function, args) do
+    :erlang.apply(module, function, [pid, table | args])
+  end
 end

lib/eternal/priv.ex

@@ -82,4 +82,15 @@ defmodule Eternal.Priv do
       is_list(unquote(opts))
     end
   end
+
+  @doc """
+  Determines if a 3-tuple is a {module, function, args}
+  """
+  defmacro is_mfa(module, function, args) do
+    quote do
+     is_atom(unquote(module)) and
+     is_atom(unquote(function)) and
+     is_list(unquote(args))
+    end
+  end
 end

lib/eternal/supervisor.ex

@@ -57,7 +57,7 @@ defmodule Eternal.Supervisor do
       worker(Eternal.Server, [{ table, flags, base }], id: Server.Two)
     ]
 
-    supervise(children, strategy: :one_for_one)
+    Supervisor.init(children, strategy: :one_for_one)
   end
 
   # Detects a potential name clash inside ETS. If we have a named table and the

mix.exs

@@ -23,8 +23,8 @@ defmodule Eternal.Mixfile do
         },
         maintainers: [ "Isaac Whitfield" ]
       },
-      version: "1.2.1",
-      elixir: "~> 1.2",
+      version: "1.3.0",
+      elixir: "~> 1.5",
       deps: deps(),
       docs: [
         extras: [ "README.md" ],

test/eternal_test.exs

@@ -12,6 +12,30 @@ defmodule EternalTest do
     assert(:ets.info(:table_with_options, :compressed) == true)
   end
 
+  def callback_fun(_pid, table) do
+    require Logger
+
+    Logger.debug to_string(table)
+  end
+
+  test "starting with an MFA callback" do
+    msg = capture_log(fn ->
+      Eternal.start_link Eternal, [], callback: {__MODULE__, :callback_fun, []}, quiet: true
+    end)
+
+    assert msg =~ "Eternal"
+  end
+
+  test "starting with a function capture callback" do
+    require Logger
+
+    msg = capture_log(fn ->
+      Eternal.start_link Eternal, [], callback: fn pid, table -> callback_fun(pid, table) end, quiet: true
+    end)
+
+    assert msg =~ "Eternal"
+  end
+
   test "starting a table with no link" do
     spawn(fn ->
       Eternal.start(:unlinked, [], [ quiet: true ])