From b15174f23827158b117cbcd3d6a89a550cb076ef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Baptiste=20Clavi=C3=A9?= <clavie.b@gmail.com>
Date: Tue, 10 Jun 2014 16:02:44 +0200
Subject: [PATCH] Fixes #17 : Add a ChangeInterface

---
 src/AbstractChange.php  |  2 +-
 src/ChangeInterface.php | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 src/ChangeInterface.php

diff --git a/src/AbstractChange.php b/src/AbstractChange.php
index 11f676a..2bb850a 100644
--- a/src/AbstractChange.php
+++ b/src/AbstractChange.php
@@ -17,7 +17,7 @@
  * @author Baptiste Clavié <clavie.b@gmail.com>
  * @author Rémy Gazelot <rgazelot@gmail.com>
  */
-abstract class AbstractChange
+abstract class AbstractChange implements ChangeInterface
 {
     /** old state */
     private $old;
diff --git a/src/ChangeInterface.php b/src/ChangeInterface.php
new file mode 100644
index 0000000..f40e3cd
--- /dev/null
+++ b/src/ChangeInterface.php
@@ -0,0 +1,27 @@
+<?php
+/**
+ * This file is part of the Totem package
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ *
+ * @copyright Baptiste Clavié <clavie.b@gmail.com>
+ * @license   http://www.opensource.org/licenses/MIT-License MIT License
+ */
+
+namespace Totem;
+
+/**
+ * Represent a change in a data, with both values (before and after it was modified)
+ *
+ * @author Baptiste Clavié <clavie.b@gmail.com>
+ */
+interface ChangeInterface
+{
+    /** @return mixed the data before it was changed */
+    public function getOld();
+
+    /** @return mixed the data after it was changed */
+    public function getNew();
+}
+