future::future(NULL, lazy = TRUE) doesn't return a worker object

[njtierney]

Hi there!

We used to have a pattern like the one below:

f_thing <- future::future(NULL, lazy = TRUE)

names(f_thing)
#>  [1] "label"         "local"         "owner"         "envir"        
#>  [5] "packages"      "gc"            "conditions"    "expr"         
#>  [9] "uuid"          "seed"          "version"       "result"       
#> [13] "asynchronous"  "calls"         "globals"       "stdout"       
#> [17] "earlySignal"   "lazy"          "state"         ".defaultLocal"

f_thing$workers
#> NULL

^{Created on 2021-11-02 by the reprex package (v2.0.1)}

Session info

sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#>  setting  value                       
#>  version  R version 4.1.1 (2021-08-10)
#>  os       macOS Big Sur 10.16         
#>  system   x86_64, darwin17.0          
#>  ui       X11                         
#>  language (EN)                        
#>  collate  en_AU.UTF-8                 
#>  ctype    en_AU.UTF-8                 
#>  tz       Australia/Perth             
#>  date     2021-11-02                  
#> 
#> ─ Packages ───────────────────────────────────────────────────────────────────
#>  package     * version date       lib source        
#>  backports     1.2.1   2020-12-09 [1] CRAN (R 4.1.0)
#>  cli           3.1.0   2021-10-27 [1] CRAN (R 4.1.1)
#>  codetools     0.2-18  2020-11-04 [1] CRAN (R 4.1.1)
#>  crayon        1.4.1   2021-02-08 [1] CRAN (R 4.1.0)
#>  digest        0.6.28  2021-09-23 [1] CRAN (R 4.1.0)
#>  ellipsis      0.3.2   2021-04-29 [1] CRAN (R 4.1.0)
#>  evaluate      0.14    2019-05-28 [1] CRAN (R 4.1.0)
#>  fansi         0.5.0   2021-05-25 [1] CRAN (R 4.1.0)
#>  fastmap       1.1.0   2021-01-25 [1] CRAN (R 4.1.0)
#>  fs            1.5.0   2020-07-31 [1] CRAN (R 4.1.0)
#>  future        1.23.0  2021-10-31 [1] CRAN (R 4.1.1)
#>  globals       0.14.0  2020-11-22 [1] CRAN (R 4.1.0)
#>  glue          1.4.2   2020-08-27 [1] CRAN (R 4.1.0)
#>  highr         0.9     2021-04-16 [1] CRAN (R 4.1.0)
#>  htmltools     0.5.2   2021-08-25 [1] CRAN (R 4.1.0)
#>  knitr         1.36    2021-09-29 [1] CRAN (R 4.1.0)
#>  lifecycle     1.0.1   2021-09-24 [1] CRAN (R 4.1.0)
#>  listenv       0.8.0   2019-12-05 [1] CRAN (R 4.1.0)
#>  magrittr      2.0.1   2020-11-17 [1] CRAN (R 4.1.0)
#>  parallelly    1.28.1  2021-09-09 [1] CRAN (R 4.1.0)
#>  pillar        1.6.4   2021-10-18 [1] CRAN (R 4.1.0)
#>  pkgconfig     2.0.3   2019-09-22 [1] CRAN (R 4.1.0)
#>  purrr         0.3.4   2020-04-17 [1] CRAN (R 4.1.0)
#>  R.cache       0.15.0  2021-04-30 [1] CRAN (R 4.1.0)
#>  R.methodsS3   1.8.1   2020-08-26 [1] CRAN (R 4.1.0)
#>  R.oo          1.24.0  2020-08-26 [1] CRAN (R 4.1.0)
#>  R.utils       2.11.0  2021-09-26 [1] CRAN (R 4.1.0)
#>  reprex        2.0.1   2021-08-05 [1] CRAN (R 4.1.0)
#>  rlang         0.4.12  2021-10-18 [1] CRAN (R 4.1.0)
#>  rmarkdown     2.11    2021-09-14 [1] CRAN (R 4.1.0)
#>  rstudioapi    0.13    2020-11-12 [1] CRAN (R 4.1.0)
#>  sessioninfo   1.1.1   2018-11-05 [1] CRAN (R 4.1.0)
#>  stringi       1.7.5   2021-10-04 [1] CRAN (R 4.1.0)
#>  stringr       1.4.0   2019-02-10 [1] CRAN (R 4.1.0)
#>  styler        1.6.2   2021-09-23 [1] CRAN (R 4.1.0)
#>  tibble        3.1.5   2021-09-30 [1] CRAN (R 4.1.0)
#>  utf8          1.2.2   2021-07-24 [1] CRAN (R 4.1.0)
#>  vctrs         0.3.8   2021-04-29 [1] CRAN (R 4.1.0)
#>  withr         2.4.2   2021-04-18 [1] CRAN (R 4.1.0)
#>  xfun          0.26    2021-09-14 [1] CRAN (R 4.1.0)
#>  yaml          2.2.1   2020-02-01 [1] CRAN (R 4.1.0)
#> 
#> [1] /Library/Frameworks/R.framework/Versions/4.1/Resources/library

However it appears that workers doesn't exist in this object, I just wanted to check if there is another name for this name/slot? I couldn't find this in the NEWS file.

For full details I've posted a bit more detail about the break in the greta repo: greta-dev/greta#447

[HenrikBengtsson]

Hello. This is expected; not all types of Future object has an element workers, and if it does, it's not part of the public API. As a matter of fact, no elements are part of the public API.