Great tutorial! quick question on after_stat.

Line 193 in ef59259

ggplot(mpg) +

Just trying to stretch the new functionalities of after_stat. It is already much clear than its predecessors. Yet maybe I am mistaken, after_stat currently do not seem to be able to take named functions. I tried to look into the error message and source code but tidy evaluation is a bit hard for me to pin down. Is that a current limitation? Wonder if I can help?

library(ggplot2)
percentage <- function() count / sum(count)
ggplot(mpg) + 
  geom_bar(aes(x = class, y = after_stat((function() count / sum(count))())))

ggplot(mpg) + 
  geom_bar(aes(x = class, y = after_stat((percentage)())))
#> Error in (percentage)(): object 'count' not found

^{Created on 2020-04-04 by the reprex package (v0.3.0)}

library(ggplot2)
library(rlang)
percentage <- function() {
  count <- enquo(count)
  expr(!!count / sum(!!count)) 
}

ggplot(mpg) + 
  geom_bar(aes(x = class, y = after_stat(eval_tidy(percentage()))))
#> Error in (function (x) : object 'count' not found

^{Created on 2020-04-04 by the reprex package (v0.3.0)}