函数删除我的tibble的自定义类

Question

library(tidyverse)
#> Warning: package 'tidyverse' was built under R version 3.4.2
#> ── Attaching packages ─────────────────────────────────────────────────────────────────────────── tidyverse 1.2.1 ──
#> ✔ ggplot2 2.2.1     ✔ purrr   0.2.4
#> ✔ tibble  1.4.2     ✔ dplyr   0.7.4
#> ✔ tidyr   0.8.0     ✔ stringr 1.2.0
#> ✔ readr   1.1.1     ✔ forcats 0.2.0
#> Warning: package 'tibble' was built under R version 3.4.3
#> Warning: package 'tidyr' was built under R version 3.4.3
#> Warning: package 'purrr' was built under R version 3.4.2
#> Warning: package 'dplyr' was built under R version 3.4.2
#> ── Conflicts ────────────────────────────────────────────────────────────────────────────── tidyverse_conflicts() ──
#> ✖ dplyr::filter() masks stats::filter()
#> ✖ dplyr::lag()    masks stats::lag()

tmp <- as_tibble(mtcars) %>% structure(class = c(class(.), "other_class"))

class(tmp)
#> [1] "tbl_df"      "tbl"         "data.frame"  "other_class"

tmp %>% arrange(mpg) %>% class()
#> [1] "tbl_df"     "tbl"        "data.frame"

如何允许其他任何功能保留此other_class？我知道this和this，但我似乎无法理解它。任何提示？