php 导出对象生成代码并执行var_export和eval

<?php
class Person
{
	private $name;
	private $age;
	public function __construct($name,$age)
	{
		$this->name = $name;
		$this->age = $age;
	}	
	static function __set_state($arr)
	{
		$p = new Person($arr[‘name‘],$arr[‘age‘]);
		$p->name = "ls";
		$p->age = 20;
		return $p;
	}
	
	function __toString()
	{
		return $this->name."{$this->age}";
	}
}
$a = new Person("zs",10);
echo $a;
echo ‘<br>‘;
$str = var_export($a,true);
eval(‘$b=‘.$str.‘;‘);
echo $b;