`[[.ggproto` has atypical argument names

[teunbrand]

This is really a minor thing, but the [[.ggproto() function has name as the index argument instead of i.
This is fine for everyday use of [[-indexing, but becomes a mild annoyance when trying to programmatically extract something from a list of ggproto objects.

library(ggplot2)

# Simple function for extracting the same thing from a list of things
extract <- function(x, what) {
  lapply(x, `[[`, i = what)
}

# Works fine
x <- list(list(limits = c(NA, NA)), list(limits = c("A", "B")))
extract(x, "limits")
#> [[1]]
#> [1] NA NA
#> 
#> [[2]]
#> [1] "A" "B"

x <- list(
  scale_x_continuous(limits = c(NA, NA)), 
  scale_color_brewer(limits = c("A", "B"))
)
extract(x, "limits")
#> Error in `[[.ggproto`(X[[i]], ...): unused argument (i = "limits")

# Can fix this by changing `i` to `name`
lapply(x, `[[`, name = "limits")
#> [[1]]
#> [1] NA NA
#> 
#> [[2]]
#> [1] "A" "B"

^{Created on 2023-10-11 with reprex v2.0.2}

[mjskay]

Since the [[ primitive ignores the names of arguments and only considers position, I'd think the correct idiom in both cases would be lapply(x, `[[`, what)?

> x = list("a")
> `[[`(x, 1)
[1] "a"
> `[[`(x, i = 1)
[1] "a"
> `[[`(x, name = 1)
[1] "a"
> `[[`(i = 1, x)
Error in 1[[x]] : invalid subscript type 'list'

(which is not to say that the index argument name shouldn't be i)

[teunbrand]

Yeah you make a fair point, let's just close this.