Changing the name in the lhs with rlang

rlang_misc.R

library(rlang)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union

# using objects for list names, when you dont want to go [[ route
x <- "foo"
y <- "bar"

list2(
  !!sym(x) := 1,
  !!sym(y) := 2
)
#> $foo
#> [1] 1
#> 
#> $bar
#> [1] 2

# lhs variables with mutate
# src: https://speakerdeck.com/lionelhenry/interactivity-and-programming-in-the-tidyverse
mean_by <- function(data, by, var, var_name) {
  data %>% 
    group_by({{ by }}) %>% 
    summarise({{ var_name }} := mean({{ var }}))
}

iris %>% 
  mean_by(Species, Sepal.Width, "custom_name")
#> `summarise()` ungrouping output (override with `.groups` argument)
#> # A tibble: 3 x 2
#>   Species    custom_name
#>   <fct>            <dbl>
#> 1 setosa            3.43
#> 2 versicolor        2.77
#> 3 virginica         2.97

sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#>  setting  value                       
#>  version  R version 4.0.3 (2020-10-10)
#>  os       macOS Catalina 10.15.7      
#>  system   x86_64, darwin17.0          
#>  ui       X11                         
#>  language (EN)                        
#>  collate  en_US.UTF-8                 
#>  ctype    en_US.UTF-8                 
#>  tz       America/Los_Angeles         
#>  date     2020-12-18                  
#> 
#> ─ Packages ───────────────────────────────────────────────────────────────────
#>  package     * version date       lib source        
#>  assertthat    0.2.1   2019-03-21 [2] CRAN (R 4.0.2)
#>  cli           2.0.2   2020-02-28 [2] CRAN (R 4.0.2)
#>  crayon        1.3.4   2017-09-16 [2] CRAN (R 4.0.2)
#>  digest        0.6.27  2020-10-24 [1] CRAN (R 4.0.2)
#>  dplyr       * 1.0.2   2020-08-18 [1] CRAN (R 4.0.2)
#>  ellipsis      0.3.1   2020-05-15 [2] CRAN (R 4.0.2)
#>  evaluate      0.14    2019-05-28 [1] CRAN (R 4.0.1)
#>  fansi         0.4.1   2020-01-08 [2] CRAN (R 4.0.2)
#>  generics      0.0.2   2018-11-29 [1] CRAN (R 4.0.2)
#>  glue          1.4.2   2020-08-27 [2] CRAN (R 4.0.2)
#>  highr         0.8     2019-03-20 [1] CRAN (R 4.0.2)
#>  htmltools     0.5.0   2020-06-16 [1] CRAN (R 4.0.2)
#>  knitr         1.30    2020-09-22 [1] CRAN (R 4.0.2)
#>  lifecycle     0.2.0   2020-03-06 [2] CRAN (R 4.0.2)
#>  magrittr      1.5     2014-11-22 [2] CRAN (R 4.0.2)
#>  pillar        1.4.6   2020-07-10 [2] CRAN (R 4.0.2)
#>  pkgconfig     2.0.3   2019-09-22 [2] CRAN (R 4.0.2)
#>  purrr         0.3.4   2020-04-17 [2] CRAN (R 4.0.2)
#>  R6            2.5.0   2020-10-28 [1] CRAN (R 4.0.2)
#>  rlang       * 0.4.8   2020-10-08 [2] CRAN (R 4.0.2)
#>  rmarkdown     2.5     2020-10-21 [1] CRAN (R 4.0.2)
#>  sessioninfo   1.1.1   2018-11-05 [1] CRAN (R 4.0.2)
#>  stringi       1.5.3   2020-09-09 [1] CRAN (R 4.0.2)
#>  stringr       1.4.0   2019-02-10 [1] CRAN (R 4.0.2)
#>  tibble        3.0.3   2020-07-10 [2] CRAN (R 4.0.2)
#>  tidyselect    1.1.0   2020-05-11 [1] CRAN (R 4.0.2)
#>  utf8          1.1.4   2018-05-24 [2] CRAN (R 4.0.2)
#>  vctrs         0.3.4   2020-08-29 [2] CRAN (R 4.0.2)
#>  withr         2.3.0   2020-09-22 [2] CRAN (R 4.0.2)
#>  xfun          0.19    2020-10-30 [1] CRAN (R 4.0.2)
#>  yaml          2.2.1   2020-02-01 [2] CRAN (R 4.0.2)
#> 
#> [1] /Users/tlittlef/Library/R/4.0/library
#> [2] /Library/Frameworks/R.framework/Versions/4.0/Resources/library