Extract display into supervision tree.

lib/display.ex

@@ -1,21 +1,80 @@
 defmodule Display do
-  alias IO.ANSI
-  alias Display.ProgressBar
-  alias Display.Intro
-  alias Display.Failure
-  alias Display.Notifications
+  use GenServer
 
-  def invalid_koan(koan, modules) do
+  alias IO.ANSI
+  alias Display.{ProgressBar, Intro, Failure, Notifications}
+
+  def start_link do
+    GenServer.start_link(__MODULE__, %{clear_screen: true}, name: __MODULE__)
+  end
+
+  def disable_clear do
+    GenServer.cast(__MODULE__, :disable_clear)
+  end
+
+  def handle_cast(:disable_clear, state) do
+    {:noreply, %{state | clear_screen: false}}
+  end
+
+  def handle_cast({:invalid, koan, modules}, state) do
     Notifications.invalid_koan(koan, modules)
     |> IO.puts
+
+    {:noreply, state}
+  end
+
+  def handle_cast({:show_failure, failure, module, name}, state) do
+    format(failure, module, name)
+    |> IO.puts
+
+    {:noreply, state}
+  end
+
+  def handle_cast({:show_compile_error, error}, state) do
+    Failure.show_compile_error(error)
+    |> IO.puts
+
+    {:noreply, state}
+  end
+
+  def handle_cast(:congratulate, state) do
+    Notifications.congratulate
+    |> IO.puts
+
+    {:noreply, state}
+  end
+
+  def handle_cast(:clear_screen, state = %{clear_screen: true}) do
+    IO.puts(ANSI.clear)
+    IO.puts(ANSI.home)
+
+    {:noreply, state}
+  end
+  def handle_cast(:clear_screen, state) do
+    {:noreply, state}
+  end
+
+  def invalid_koan(koan, modules) do
+    GenServer.cast(__MODULE__, {:invalid, koan, modules})
   end
 
   def show_failure(failure, module, name) do
-    format(failure, module, name)
-    |> IO.puts
+    GenServer.cast(__MODULE__, {:show_failure, failure, module, name})
   end
 
-  def format(failure, module, name) do
+  def show_compile_error(error) do
+    GenServer.cast(__MODULE__, {:show_compile_error, error})
+  end
+
+  def congratulate do
+    GenServer.cast(__MODULE__, :congratulate)
+  end
+
+  def clear_screen do
+    GenServer.cast(__MODULE__, :clear_screen)
+  end
+
+  defp format(failure, module, name) do
     """
     #{Intro.intro(module, Tracker.visited)}
     Now meditate upon #{format_module(module)}
@@ -26,23 +85,6 @@ defmodule Display do
     """
   end
 
-  def show_compile_error(error) do
-    Failure.show_compile_error(error)
-    |> IO.puts
-  end
-
-  def congratulate do
-    Notifications.congratulate
-    |> IO.puts
-  end
-
-  def clear_screen do
-    if Options.clear_screen? do
-      IO.puts(ANSI.clear)
-      IO.puts(ANSI.home)
-    end
-  end
-
   defp format_module(module) do
     Module.split(module) |> List.last
   end

lib/elixir_koans.ex

@@ -0,0 +1,15 @@
+defmodule ElixirKoans do
+  use Application
+  alias Options
+
+  def start(_type, _args) do
+    import Supervisor.Spec
+
+    children = [
+      worker(Display, [])
+    ]
+
+    opts = [strategy: :one_for_one, name: ElixirKoans.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+end

lib/meditate.ex

@@ -12,6 +12,11 @@ defmodule Mix.Tasks.Meditate do
 
     Options.start(args)
 
+    {parsed, _, _} = OptionParser.parse(args)
+    if Keyword.has_key?(parsed, :no_clear_screen) do
+      Display.disable_clear()
+    end
+
     Options.initial_koan
     |> ok?
     |> Runner.modules_to_run

lib/options.ex

@@ -1,6 +1,5 @@
 defmodule Options do
   @defaults %{
-    clear_screen: true,
     initial_koan: Equalities,
   }
 
@@ -8,16 +7,8 @@ defmodule Options do
     Agent.start_link(fn -> parse(args) end, name: __MODULE__)
   end
 
-  def clear_screen? do
-    Agent.get(__MODULE__, fn(options) ->
-      Map.fetch!(options, :clear_screen)
-    end)
-  end
-
   def initial_koan() do
-    Agent.get(__MODULE__, fn(options) ->
-      Map.fetch!(options, :initial_koan)
-    end)
+    Agent.get(__MODULE__, &Map.fetch!(&1, :initial_koan))
   end
 
   defp parse(args) do
@@ -27,6 +18,5 @@ defmodule Options do
   end
 
   def parse_argument("--koan="<>module), do: %{ initial_koan: String.to_atom("Elixir."<> module)}
-  def parse_argument("--no-clear-screen"), do: %{ clear_screen: false}
   def parse_argument(_), do: %{}
 end

mix.exs

@@ -10,7 +10,8 @@ defmodule Koans.Mixfile do
   end
 
   def application do
-    [applications: [:exfswatch, :logger]]
+    [mod: {ElixirKoans, []},
+     applications: [:exfswatch, :logger]]
   end
 
   defp deps do

test/options_test.exs

@@ -1,23 +1,8 @@
 defmodule OptionTest do
   use ExUnit.Case, async: true
 
-  test "has default options" do
-    Options.start([])
-    assert Options.clear_screen?
-  end
-
-  test "override clearing of screen" do
-    Options.start(["--no-clear-screen"])
-    refute Options.clear_screen?
-  end
-
   test "can target specifc koans" do
     Options.start(["--koan=Strings"])
     assert Options.initial_koan() == Strings
   end
-
-  test "ignores unknown options" do
-    Options.start(["--foo"])
-    assert Options.clear_screen?
-  end
 end