PHP7 Adapter

Structural/Adapter/Book.php

@@ -2,22 +2,25 @@
 
 namespace DesignPatterns\Structural\Adapter;
 
-/**
- * Book is a concrete and standard paper book.
- */
-class Book implements PaperBookInterface
+class Book implements BookInterface
 {
     /**
-     * {@inheritdoc}
+     * @var int
      */
+    private $page;
+
     public function open()
     {
+        $this->page = 1;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function turnPage()
     {
+        $this->page++;
+    }
+
+    public function getPage(): int
+    {
+        return $this->page;
     }
 }