The views should be declared based on class name, so an object of class "a: : Beta" could have a different dynamic view from "a: : Gamma" without any extra work on the programmer's part.

视图的声明应该基于类名，所以类“A： Beta”的一个对象可以有与“A： Gamma”不同的动态视图，而不需要程序员付出额外的工作。

youdao

My "enrichment1" class at school taught me how to do homework and review for tests, and my teachers gave me extra time to do class work.

在学校里我的“补习课”教我如何做作业，如何进行复习以对付考试。我的老师给了我额外的时间做课堂作业。

youdao

They do not have special lessons as such but meet once a month after school - rising to once a week in their third year - to learn study skills and take on extra work they would not be able to do in a whole-ability class, a recent example being chromatography in chemistry.

BBC: News | Education | Extra help for gifted pupils divides heads