看了官网的答案,似乎有点理解了..感觉好怪异..
In the above example, SelectableControl contains all of the members of Control, including the private stateproperty. Since state is a private member it is only possible for descendants of Control to implement SelectableControl. This is because only descendants of Control will have a state private member that originates in the same declaration, which is a requirement for private members to be compatible.
意思是这个接口继承了这个类,但是它实现的这个既然是个私有属性,那么只有这个它继承的类的才能访问这个属性.因此也就意味着任意一个类实现这个接口的同时必须要继承该接口所继承的类..有点绕...是这个意思吗老师...这样做等于隐式将一个接口和类做了绑定可以这样理解么.