Chore: standardize one-liner ggproto methods to use `{`

[yjunechoe]

There are some inconsistencies in how one-liner ggproto methods are written, with and without {. As far as I can tell, { for one-liners seems like an arbitrary stylistic choice in the source code

library(ggplot2)

Geom$setup_data
#> <ggproto method>
#>   <Wrapper function>
#>     function (...) 
#> setup_data(...)
#> 
#>   <Inner function (f)>
#>     function (data, params) 
#> data

Stat$setup_data
#> <ggproto method>
#>   <Wrapper function>
#>     function (...) 
#> setup_data(...)
#> 
#>   <Inner function (f)>
#>     function (data, params) 
#> {
#>     data
#> }

It's my understanding that starting a function body with { is more standard. It lets methods show up on the RStudio outline pane and also some debugging functions require it (ex: trace() with an at argument).

A quick search finds a few hits for one-liners without { like Geom$setup_data:

library(ggplot2)
ggprotos <- mget(ls("package:ggplot2"), asNamespace("ggplot2"), ifnotfound = list(NULL)) |>
  Filter(\(x) inherits(x, "ggproto"), x = _)
ggproto_methods_nobrackets <- lapply(ggprotos, \(x) {
  Filter(
    \(m) inherits(x[[m]], "ggproto_method") &&
      length(body(get(m, x))) == 1,
    ls(envir = x)
  )
})
sum(lengths(ggproto_methods_nobrackets))
#> [1] 19
Filter(length, ggproto_methods_nobrackets)
#> $Coord
#> [1] "is_free"   "is_linear"
#> 
#> $CoordCartesian
#> [1] "is_free"   "is_linear"
#> 
#> $CoordFixed
#> [1] "is_free"
#> 
#> $CoordPolar
#> [1] "aspect"  "is_free"
#> 
#> $CoordRadial
#> [1] "is_free"
#> 
#> $CoordSf
#> [1] "is_free" "labels" 
#> 
#> $CoordTrans
#> [1] "is_free"
#> 
#> $Geom
#> [1] "setup_data"   "setup_params"
#> 
#> $GeomBlank
#> [1] "draw_panel" "handle_na" 
#> 
#> $ScaleBinned
#> [1] "is_discrete"
#> 
#> $ScaleContinuous
#> [1] "is_discrete"
#> 
#> $ScaleDiscrete
#> [1] "is_discrete" "transform"

This should be a trivial, non-intrusive chore that's easy to unit test. I'm happy to PR this if it seems within scope!

[teunbrand]

Thanks for the issue June! I believe from our prior discussion that one-liners are also untrace()able, right? In any case, if it is harmless and { is preferred, I see no obstacles for a PR :)