Most of the classes used in WordPress are Singletons (the entire functionality is contained in a single class), but often require initializing of properties manually.

• 新的附加类和一些外部的库使用多种类来组成有某种功能的库。这创建了一个更高的学习曲线，因为基类(开发者用来提供从所有其他类获得其功能的类)不清楚。