ARROW-14575 [R] Allow functions with {{pkg::}} prefixes - second approach

[dragosmg]

Same goal as #13160, namely to allow the use of namespacing with bindings:

library(arrow, warn.conflicts = FALSE)
library(dplyr, warn.conflicts = FALSE)
library(lubridate, warn.conflicts = FALSE)

test_df <- tibble(
  date = as.Date(c("2022-03-22", "2021-07-30", NA))
)

test_df %>%
  mutate(ddate = lubridate::as_datetime(date)) %>%
  collect()
#> # A tibble: 3 × 2
#>   date       ddate              
#>   <date>     <dttm>             
#> 1 2022-03-22 2022-03-22 00:00:00
#> 2 2021-07-30 2021-07-30 00:00:00
#> 3 NA         NA

test_df %>%
  arrow_table() %>% 
  mutate(ddate = lubridate::as_datetime(date)) %>%
  collect()
#> # A tibble: 3 × 2
#>   date       ddate              
#>   <date>     <dttm>             
#> 1 2022-03-22 2022-03-22 00:00:00
#> 2 2021-07-30 2021-07-30 00:00:00
#> 3 NA         NA

^{Created on 2022-05-14 by the reprex package (v2.0.1)}

The approach (option 2):

• each binding is registered only once, as pkg::fun() and we change the way we look up a binding

Steps:

• add functionality to allow binding registration with the pkg::fun() name;
  • register_binding() registers a single, prefixed copy of fun, pkg::fun.
  • Add a binding for the :: operator, which helps with retrieving bindings from the function registry.
  • Add generic unit tests for the pkg::fun functionality.
  • Throw a classed error ("arrow-binding-error") if fun is not found and look it up again, this time as ::fun. All of:
    • mutate()
    • filter(), and
    • summarise() should able to handle this new error class
• register nse_funcs requiring indirect mapping
  • register each binding with the corresponding pkg:: prefix.
  • add / update unit tests for the nse_funcs bindings to include at least one pkg::fun() call for each binding
• register nse_funcs requiring direct mapping (unary and binary bindings)
  • register unary bindings
  • register binary bindings
  • add / update unit tests for the nse_funcs bindings to include at least one pkg::fun() call for each binding
• document changes in the Writing bindings documentation
  • going forward we should be using pkg::fun when defining a binding.

Bindings that will not be registered with a pkg:: prefix:

• type casting, such as cast() or dictionary_encode()
• operators (e.g. "!", "==", "!=", ">", ">=", "<", "<=", "&", etc.)
• aggregating functions(e.g. sum, any, all, mean, sd, var, etc)
  • something fails when extracting all function calls in an expression with all_funs(). For example, in dplyr::n(), only :: is identified as a function call by all_funs() and {arrow}'s is_function().

[github-actions]

https://issues.apache.org/jira/browse/ARROW-14575