r - 文字列変数を forcats::fct_reorder に渡す

Question

文字列の並べ替え変数をに渡す方法はありますfct_reorderか?

require(dplyr)
require(forcats)
require(ggplot2)

order_var = 'displ'

mpg %>% mutate(manufacturer = fct_reorder(manufacturer, order_var))
#> Error in mutate_impl(.data, dots): Evaluation error: length(f) == length(.x) is not TRUE.

で試しましたbang bang !!：

mpg %>% mutate(manufacturer = fct_reorder(manufacturer, !!order_var))
#> Error in mutate_impl(.data, dots): Evaluation error: length(f) == length(.x) is not TRUE.

で試しましたeval：

as.name(eval(order_var))
#> displ

mpg %>% mutate(manufacturer = fct_reorder(manufacturer, as.name(eval(order_var))))
#> Error in mutate_impl(.data, dots): Evaluation error: length(f) == length(.x) is not TRUE.

助言がありますか？