added flyweight pattern

Structural/Flyweight/FlyweightFactory.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace DesignPatterns\Structural\Flyweight;
+
+use DesignPatterns\Structural\Flyweight\CharacterFlyweight;
+
+/**
+ * A factory manages shared flyweights. Clients shouldn't instaniate them directly,
+ * but let the factory take care of returning existing objects or creating new ones.
+ */
+class FlyweightFactory {
+	
+	/**
+	 * Associative store for flyweight objects
+     * @var Array
+     */
+	private $pool = array();
+
+	/**
+     * Magic getter
+     * @param string $name
+     * @return Flyweight
+     */
+    public function __get($name)
+    {
+        if (!array_key_exists((string) $name, $this->pool)) {
+            $this->pool[(string) $name] = new CharacterFlyweight((string) $name);
+        }
+        return $this->pool[(string) $name];
+    }
+
+    public function totalNumber()
+    {
+    	return sizeof($this->pool);
+    }
+
+}