Naturally this approach requires a bit more work on the User’s part: if there are M users on the banned list, then every User must do about M extra pieces of work when Showing their credential, which hopefully means that the number of banned users stays small.
Strict vs. Lazy，详情可参考旺商聊官方下载
inside the hot loop in a real system but only use primitive types to store the projected values.，推荐阅读safew官方下载获取更多信息
差距不是在缩小，而是在指数级扩大。