Why does expr_text() behave differently for variables containing non-ASCII characters?

[yutannihilation]

(original issue: tidyverse/ggplot2#3017)

If the expression is a symbol and it has any non-ASCII characters, expr_text() adds backticks except when the character is at the head of the variable name. I'm failing to see the rule behind this... Is this intended? I feel backticks should not be added at all as long as the characters are representable in the current locale.

library(rlang)

expr_text(sym("áa"))
#> [1] "áa"
expr_text(sym("aá"))
#> [1] "`aá`"
as_string(sym("aá"))
#> [1] "aá"

aá <- 1
aá
#> [1] 1

^{Created on 2018-11-27 by the reprex package (v0.2.1)}

Session info

devtools::session_info()
#> ─ Session info ──────────────────────────────────────────────────────────
#>  setting  value                       
#>  version  R version 3.5.1 (2018-07-02)
#>  os       macOS High Sierra 10.13.6   
#>  system   x86_64, darwin15.6.0        
#>  ui       X11                         
#>  language en                          
#>  collate  ja_JP.UTF-8                 
#>  ctype    ja_JP.UTF-8                 
#>  tz       Asia/Tokyo                  
#>  date     2018-11-27                  
#> 
#> ─ Packages ──────────────────────────────────────────────────────────────
#>  package     * version    date       lib source                      
#>  assertthat    0.2.0      2017-04-11 [1] CRAN (R 3.5.0)              
#>  backports     1.1.2      2017-12-13 [1] CRAN (R 3.5.0)              
#>  base64enc     0.1-3      2015-07-28 [1] CRAN (R 3.5.0)              
#>  callr         3.0.0      2018-08-24 [1] CRAN (R 3.5.0)              
#>  cli           1.0.1      2018-09-25 [1] CRAN (R 3.5.0)              
#>  crayon        1.3.4      2017-09-16 [1] CRAN (R 3.5.0)              
#>  desc          1.2.0      2018-05-01 [1] CRAN (R 3.5.0)              
#>  devtools      2.0.1      2018-10-26 [1] CRAN (R 3.5.1)              
#>  digest        0.6.18     2018-10-10 [1] CRAN (R 3.5.1)              
#>  evaluate      0.12       2018-10-09 [1] CRAN (R 3.5.0)              
#>  fs            1.2.6      2018-08-23 [1] CRAN (R 3.5.0)              
#>  glue          1.3.0      2018-07-17 [1] CRAN (R 3.5.1)              
#>  highr         0.7        2018-06-09 [1] CRAN (R 3.5.0)              
#>  htmltools     0.3.6      2017-04-28 [1] CRAN (R 3.5.0)              
#>  knitr         1.20.22    2018-11-26 [1] local                       
#>  magrittr      1.5        2014-11-22 [1] CRAN (R 3.5.0)              
#>  memoise       1.1.0      2017-04-21 [1] CRAN (R 3.5.0)              
#>  pkgbuild      1.0.2      2018-10-16 [1] CRAN (R 3.5.0)              
#>  pkgload       1.0.2      2018-10-29 [1] CRAN (R 3.5.0)              
#>  prettyunits   1.0.2      2015-07-13 [1] CRAN (R 3.5.0)              
#>  processx      3.2.0      2018-08-16 [1] CRAN (R 3.5.0)              
#>  ps            1.2.1      2018-11-06 [1] CRAN (R 3.5.1)              
#>  R6            2.3.0      2018-10-04 [1] CRAN (R 3.5.0)              
#>  Rcpp          1.0.0      2018-11-07 [1] CRAN (R 3.5.1)              
#>  remotes       2.0.2      2018-10-30 [1] CRAN (R 3.5.0)              
#>  rlang       * 0.3.0.9000 2018-11-27 [1] local                       
#>  rmarkdown     1.10       2018-06-11 [1] CRAN (R 3.5.0)              
#>  rprojroot     1.3-2      2018-01-03 [1] CRAN (R 3.5.0)              
#>  sessioninfo   1.1.1      2018-11-05 [1] CRAN (R 3.5.1)              
#>  stringi       1.2.4      2018-07-20 [1] CRAN (R 3.5.0)              
#>  stringr       1.3.1      2018-05-10 [1] CRAN (R 3.5.0)              
#>  testthat      2.0.1      2018-10-13 [1] CRAN (R 3.5.0)              
#>  usethis       1.4.0      2018-08-14 [1] CRAN (R 3.5.0)              
#>  withr         2.1.2.9000 2018-10-25 [1] Github (r-lib/withr@be57595)
#>  xfun          0.4        2018-10-23 [1] CRAN (R 3.5.1)              
#>  yaml          2.2.0      2018-07-25 [1] CRAN (R 3.5.0)              
#> 
#> [1] /Library/Frameworks/R.framework/Versions/3.5/Resources/library

[lionel-]

Hello Hiroaki, could you install dev rlang and take this for a spin please? I'd like to make a quick patch release soon. I have run R CMD check for dplyr on Windows and found no issues so hopefully it doesn't break anything for non-unicode locales.

[yutannihilation]

Sure, I'll do it later today or tomorrow.

[yutannihilation]

Confirmed this issue is fixed on Windows. Thanks!

library(rlang)

expr_text(sym("あa"))
#> [1] "あa"
expr_text(sym("aあ"))
#> [1] "aあ"

^{Created on 2018-12-13 by the reprex package (v0.2.1)}

(By the way, I remembered I reported this issue from macOS; On Windows in my locale á is transliterated into a, so I would never see this problem...)

[lionel-]

Thanks! Please also let me know if you see anything weird while working with dplyr/ggplot2.

[yutannihilation]

Sure 👍