The next important feature to take advantage of when migrating from PHP V4 to V5 is support for contract programming through interfaces and abstract classes and methods.

从PHP V 4迁移到PHP v5时要利用的下一个重要特性是支持通过接口、抽象类和方法进行契约编程。

youdao

Implement standard OOP features like private constructors, abstract methods and classes.

实现标准的面向对象功能，比如：私有构造函数、抽象方法和抽象类等。

youdao

The TypeDescription class is just an abstract base class with methods defined for dealing with three kinds of types: primitives, arrays, and instances of classes.

TypeDescription 类只是个抽象基类，其中定义了处理三种类型的方法：原生类型、数组和类实例。

youdao