关于适配器的使用

xyst0524

The child classes, the drivers themselves, can then be called directly through the parent class, without initializing them:
$this->some_parent->child_one->some_method();
$this->some_parent->child_two->another_method();
以及
适配器目录和文件结构布局的例子：
/application/libraries/Driver_name
Driver_name.php
drivers
Driver_name_subclass_1.php
Driver_name_subclass_2.php
Driver_name_subclass_3.php

这怎么理解，如何来使用，谁能举一个简单的例子吗？