In this case we do not define an instance variable in the injectee, but an abstract method returning the required object. The method may be public or protected
在这个例子中，我们没有在被注入者中定义一个实例变量，而是定义了一个返回所需对象的抽象方法。
2
Testers can be used in controlled experiments in which the only significant variable is one of the protected classes.
测试员可能被用来进行可控性试验，这些试验中唯一的典型变量就是受法律保护的某些阶层。
3
If you have a home loan with a variable-rate mortgage loan, that can be protected by buying out-of-the-money bond puts.