Can pass quosure to col arg in separate()

[markfairbanks]

Closes #359

[eutwt]

LGTM

[eutwt]

This fixes the linked issue and doesn't introduce any new bugs. But, when looking through this I realized separate with column numbers doesn't work in dtplyr. Would be fine to merge this and address that issue in a different PR if you want though, I think.

library(tidyr, warn.conflicts = FALSE)
library(data.table, warn.conflicts = FALSE)
library(dtplyr)

dt <- data.table(x = c("a_a", "b_b", "c_c"))
df <- as.data.frame(dt)

df %>% 
  separate(1, into = c("left", "right"))
#>   left right
#> 1    a     a
#> 2    b     b
#> 3    c     c
dt %>% 
  separate(1, into = c("left", "right"))
#> Warning: Using `as.character()` on a quosure is deprecated as of rlang 0.3.0.
#> Please use `as_label()` or `as_name()` instead.
#> This warning is displayed once per session.
#> Source: local data table [3 x 2]
#> Call:   copy(`_DT1`)[, `:=`(c("left", "right"), tstrsplit(~1, split = "[^[:alnum:]]+"))][, 
#>     .(left, right)]
#> 
#>   left  right
#>   <chr> <chr>
#> 1 1     1    
#> 2 1     1    
#> 3 1     1    
#> 
#> # Use as.data.table()/as.data.frame()/as_tibble() to access results

^{Created on 2022-06-17 by the reprex package (v2.0.1)}

[markfairbanks]

@eutwt I ended up using tidyselect::eval_select() to allow for numeric selection. I also added your recommended test, but I left out the snapshot since the error message is taken care of by tidyselect.

[eutwt]

@markfairbanks I think it should error on >1 column

library(tidyr, warn.conflicts = FALSE)
library(data.table, warn.conflicts = FALSE)
devtools::load_all("/Users/mbp/Documents/GitHub/dtp")
#> ℹ Loading dtplyr
#> Warning: package 'dplyr' was built under R version 4.1.2

dt <- data.table(x = c("a_a", "b_b", "c_c"))[, y := x]
df <- as.data.frame(dt)

df %>% 
  separate(c(x, y), into = c("left", "right")) 
#> Error in `pull_as_location2()`:
#> ! Must extract column with a single valid subscript.
#> ✖ Subscript `var` has size 2 but must be size 1.
dt %>% 
  separate(c(x, y), into = c("left", "right")) 
#> Source: local data table [3 x 3]
#> Call:   copy(`_DT1`)[, `:=`(c("left", "right"), tstrsplit(x, split = "[^[:alnum:]]+"))][, 
#>     .(y, left, right)]
#> 
#>   y     left  right
#>   <chr> <chr> <chr>
#> 1 a_a   a     a    
#> 2 b_b   b     b    
#> 3 c_c   c     c    
#> 
#> # Use as.data.table()/as.data.frame()/as_tibble() to access results

^{Created on 2022-06-17 by the reprex package (v2.0.1)}