### session
简介
Yaf_Session是Yaf对Session的包装, 实现了Iterator, ArrayAccess, Countable接口, 方便使用.
关于Yaf_Session的文档介绍：http://www.laruence.com/manual/yaf.class.session.html
使用示例：
`<?php
class IndexController extends Yaf_Controller_Abstract {
public function indexAction() {
$y_session = Yaf_Session::getInstance();
$username = $y_session->set('username','liu');
var_dump($y_session->get('username'));`
Yaf_Session
`<?php
final Yaf_Session implements Iterator , ArrayAccess , Countable {
public static Yaf_Session getInstance ( void );
public Yaf_Session start ( void );
public mixed get ( string $name = NULL );
public boolean set ( string $name ,
mixed $value );
public mixed __get ( string $name );
public boolean __set ( string $name ,
mixed $value );
public boolean has ( string $name );
public boolean del ( string $name );
public boolean __isset ( string $name );
public boolean __unset ( string $name );
}`
### cookie
目前还没有看到Yaf里面有cookie的介绍
