r-lib/backports

Small inconsistency with empty names in backports of `...names()`

Closed this issue · 5 comments

agila5 commented

Dear developers, I was working on a bug in one of my packages and I noticed a small inconsistency in the ...names() function implemented in backports vs the function included in R v4.2.1.

For example:

test1 <- function(...) {
  ...names()
}
test1("ABC")
#> [1] NA

while

bp_...names = getFromNamespace("...names", "backports")
test2 <- function(...) {
  bp_...names()
}
test2("ABC")
#> NULL

Created on 2022-02-06 by the reprex package (v2.0.1)

agila5 commented

Just a small update: I noticed that the official documentation of ...names() says that the function returns the names of the arguments passed down from a calling function using ... and the official documentation of names() says the following:

Value

For names, NULL or a character vector of the same length as x. (NULL is given if the object has no names, including for objects of types which cannot have names.

So maybe that's a small inconsistency in the official implementation of ...names()?

agila5 commented

Another discrepancy:

test1 <- function(...) {
  ...names()
}
test1(a = "b", )
#> [1] "a" NA

bp_...names = getFromNamespace("...names", "backports")
test2 <- function(...) {
  bp_...names()
}

test2(a = "b", )
#> [1] "a" ""

Created on 2022-02-10 by the reprex package (v2.0.1)

Session info 
sessioninfo::session_info()
#> - Session info ---------------------------------------------------------------
#>  setting  value
#>  version  R version 4.1.2 (2021-11-01)
#>  os       Windows 10 x64 (build 19042)
#>  system   x86_64, mingw32
#>  ui       RTerm
#>  language (EN)
#>  collate  English_United Kingdom.1252
#>  ctype    English_United Kingdom.1252
#>  tz       Europe/Berlin
#>  date     2022-02-10
#>  pandoc   2.16.2 @ C:/PROGRA~1/Pandoc/ (via rmarkdown)
#> 
#> - Packages -------------------------------------------------------------------
#>  package     * version date (UTC) lib source
#>  backports     1.4.1   2021-12-13 [1] CRAN (R 4.1.2)
#>  cli           3.1.1   2022-01-20 [1] CRAN (R 4.1.2)
#>  crayon        1.4.2   2021-10-29 [1] CRAN (R 4.1.1)
#>  digest        0.6.29  2021-12-01 [1] CRAN (R 4.1.2)
#>  ellipsis      0.3.2   2021-04-29 [1] CRAN (R 4.1.1)
#>  evaluate      0.14    2019-05-28 [1] CRAN (R 4.1.1)
#>  fansi         1.0.2   2022-01-14 [1] CRAN (R 4.1.2)
#>  fastmap       1.1.0   2021-01-25 [1] CRAN (R 4.1.1)
#>  fs            1.5.2   2021-12-08 [1] CRAN (R 4.1.2)
#>  glue          1.6.1   2022-01-22 [1] CRAN (R 4.1.2)
#>  highr         0.9     2021-04-16 [1] CRAN (R 4.1.1)
#>  htmltools     0.5.2   2021-08-25 [1] CRAN (R 4.1.1)
#>  knitr         1.37    2021-12-16 [1] CRAN (R 4.1.2)
#>  lifecycle     1.0.1   2021-09-24 [1] CRAN (R 4.1.1)
#>  magrittr      2.0.2   2022-01-26 [1] CRAN (R 4.1.2)
#>  pillar        1.7.0   2022-02-01 [1] CRAN (R 4.1.2)
#>  pkgconfig     2.0.3   2019-09-22 [1] CRAN (R 4.1.1)
#>  purrr         0.3.4   2020-04-17 [1] CRAN (R 4.1.1)
#>  R.cache       0.15.0  2021-04-30 [1] CRAN (R 4.1.1)
#>  R.methodsS3   1.8.1   2020-08-26 [1] CRAN (R 4.1.1)
#>  R.oo          1.24.0  2020-08-26 [1] CRAN (R 4.1.1)
#>  R.utils       2.11.0  2021-09-26 [1] CRAN (R 4.1.1)
#>  reprex        2.0.1   2021-08-05 [1] CRAN (R 4.1.1)
#>  rlang         1.0.1   2022-02-03 [1] CRAN (R 4.1.2)
#>  rmarkdown     2.11    2021-09-14 [1] CRAN (R 4.1.1)
#>  rstudioapi    0.13    2020-11-12 [1] CRAN (R 4.1.1)
#>  sessioninfo   1.2.2   2021-12-06 [1] CRAN (R 4.1.2)
#>  stringi       1.7.6   2021-11-29 [1] CRAN (R 4.1.2)
#>  stringr       1.4.0   2019-02-10 [1] CRAN (R 4.1.1)
#>  styler        1.6.2   2021-09-23 [1] CRAN (R 4.1.1)
#>  tibble        3.1.6   2021-11-07 [1] CRAN (R 4.1.2)
#>  utf8          1.2.2   2021-07-24 [1] CRAN (R 4.1.1)
#>  vctrs         0.3.8   2021-04-29 [1] CRAN (R 4.1.1)
#>  withr         2.4.3   2021-11-30 [1] CRAN (R 4.1.2)
#>  xfun          0.29    2021-12-14 [1] CRAN (R 4.1.2)
#>  yaml          2.2.2   2022-01-25 [1] CRAN (R 4.1.2)
#> 
#>  [1] C:/Users/andre/Documents/R/win-library/4.1
#>  [2] C:/Program Files/R/R-4.1.2/library
#> 
#> ------------------------------------------------------------------------------

Sorry for all these messages.

AshesITR commented

NB base R's alist() behaves more in line with backports.

names(alist(a = "b", ))
#> [1] "a" ""
mllg commented

I cannot reproduce the behavior of R's ...names() function on my local machine. I've added your example to the unit tests in d6ca958, they seem to work fine. I also double-checked, the implementation in base did not change AFAICT. Can you try again in a fresh session with only backports loaded? Maybe some other package is overloading ...names()?

agila5 commented

Hi @mllg and thanks for your message. I'm not 100% sure why, but I think that the bug exists only when I compare backports with R 4.1.2, whereas the problem was fixed in R 4.1.3 (maybe here: https://bugs.r-project.org/show_bug.cgi?id=18247). I successfully replicated the problem in my fork of this package: agila5#2. I solved my original problem in a different way, but I still wanted to report this slightly problematic interaction.