No base class to extend, no abstract methods to implement, no controller to coordinate with — just an object with the right shape.
You can see that the changes are only in E1, E2, and E3. The latter one is required just for completeness. The interesting change is in E2 where I no longer use a block local static but the static data member from E1. You still have the two options: user-declared and user-defined constructor.
，详情可参考搜狗输入法
A host can also define entirely custom capabilities — there is nothing special about the ones listed above.
Нина Ташевская (Редактор отдела «Среда обитания»)