start a restructure

Behavioral/NullObject/LoggerInterface.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace DesignPatterns\NullObject;
+
+/**
+ * LoggerInterface is a contract for logging something
+ * 
+ * Key feature: NullLogger MUST inherit from this interface like any other Loggers
+ */
+interface LoggerInterface
+{
+    /**
+     * @param string $str
+     *
+     * @return mixed
+     */
+    public function log($str);
+}