inheritance hierarchy

基本解释

Changing the inheritance hierarchy of an object requires a declare parents tag.
改变对象的继承层次需要一个 declare parents 标签。
There is inheritance, though: SDO understands an inheritance hierarchy among types, and given a property expecting a given type, you can assign a subtype.
但存在继承性：SDO 理解类型间的继承层次结构，给定属性要求给定类型，可指派子类型。
Given an object (such as Foo, defined below), static crosscutting makes it quite simple to create new methods, add additional constructors, and even alter the inheritance hierarchy.
给定一个对象（比如下面定义的 Foo ），静态横切使得创建新方法、添加附加的构造函数，甚至改变继承层次都变得十分简单。