Add relase 0.0.3

Author: Bernard Pietraga

chapter_18/sequence/lib/sequence/server.ex

@@ -1,31 +1,52 @@
 defmodule Sequence.Server do
+  require Logger
   use GenServer
 
-  @vsn "0"
+  @vsn "1"
+  defmodule State do
+    defstruct current_number: 0, stash_pid: nil, delta: 1
+  end
+
+  def code_change("0", old_state = {current_number, stash_pid}, _extra) do
+    new_state = %State{current_number: current_number,
+                       stash_pid: stash_pid,
+                       delta: 1
+                      }
+    Logger.info("Changing code from 0 to 1")
+    Logger.info(inspect(old_state))
+    Logger.info(inspect(new_state))
+    {:ok, new_state}
+  end
 
   # API
   def start_link(stash_pid), do:
     GenServer.start_link(__MODULE__, stash_pid, name: __MODULE__)
 
   def next_number do
-    with number = GenServer.call(__MODULE__, :next_number),
-    do: "The next number is #{number}"
+    with number = GenServer.call(__MODULE__, :next_number), do:
+      "The next number is #{number}"
   end
 
   def increment_number(delta), do:
     GenServer.cast __MODULE__, {:increment_number, delta}
 
   # GenServer implementation
   def init(stash_pid) do
-    current_number = Sequence.Stash.get_value stash_pid
-    {:ok, {current_number, stash_pid}}
+    current_number = Sequence.Stash.get_value(stash_pid)
+    {:ok, %State{current_number: current_number, stash_pid: stash_pid}}
   end
 
-  def handle_call(:next_number, _from, {current_number, stash_pid}), do:
-    {:reply, current_number, {current_number+1, stash_pid}}
-  def handle_cast({:increment_number, delta}, {current_number, stash_pid}), do:
-    {:noreply, {current_number+delta, stash_pid}}
+  def handle_call(:next_number, _from, state) do
+    {:reply,
+     state.current_number,
+     %{state | current_number: state.current_number + state.delta}}
+  end
+
+  def handle_cast({:increment_number, delta}, state) do
+    {:noreply,
+     %{state | current_number: state.current_number + delta, delta: delta}}
+  end
 
-  def terminate(_reason, {current_number, stash_pid}), do:
-    Sequence.Stash.save_value(stash_pid, current_number)
+  def terminate(_reason, state), do:
+    Sequence.Stash.save_value(state.stash_pid, state.current_number)
 end

chapter_18/sequence/mix.exs

@@ -3,7 +3,7 @@ defmodule Sequence.Mixfile do
 
   def project do
     [app: :sequence,
-     version: "0.0.2",
+     version: "0.0.3",
      elixir: "~> 1.4",
      build_embedded: Mix.env == :prod,
      start_permanent: Mix.env == :prod,