[三大特性](%E4%B8%89%E5%A4%A7%E7%89%B9%E6%80%A7.md) [魔术方法](%E9%AD%94%E6%9C%AF%E6%96%B9%E6%B3%95.md) [修饰符](%E4%BF%AE%E9%A5%B0%E7%AC%A6.md) [obj变量](obj%E5%8F%98%E9%87%8F.md)