“Attach additional responsibilities to an object dynamically keeping the same interface.Decorators provide a flexible alternative to subclassing for extending functionality.（动态地给一个对象添加一些额外的职责。就增加功能来说，装饰模式相比生成子类更为灵活。）”

“单例模式（Singleton Pattern）是一个比较简单的模式，其定义如下：Ensure a class has only one instance, and provide a global point of access to it.（确保某一个类只有一个实例，而且自行实例化并向整个系统提供这个实例。）”Excerpt From: 秦小波 著. “设计模式之禅（第 2 版）（华章原创精品）.” iBooks.