add object pool pattern

Pool/Pool.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace DesignPatterns\Pool;
+
+class Pool
+{
+
+	private $instances = array();
+    private $class;
+    
+    public function __construct($class)
+    {
+        $this->class = $class;
+    }
+
+	public function get()
+	{
+		if (count($this->instances) > 0) {
+			return array_pop($this->instances);
+		}
+
+		return new $this->class();
+	}
+
+	public function dispose($instance)
+	{
+		$this->instances[] = $instance;
+	}
+
+}
+