[R] arrow R package: multiple replacement disclaimers for str_replace_all

[baarthur]

Describe the enhancement requested

While PR #39219 introduced an error message when the user passes pattern/replacement vectors with more than one element to arrow_r_string_replace_function, I'd like to suggest two enhancements.

• First and most fundamental: add a caveat on this page, which, by the way, I use almost every day. On r/R/dplyr-funcs-doc.R:

#' * [`str_replace_all()`][stringr::str_replace_all()] Multiple replacements not yet supported,
#' `pattern`/`replacement` must be a length 1 character vector

• Second: make the validation_error() more explicit on what's happening. On r/R/dplyr-funcs-string.R:

if (length(pattern) != 1) {
        validation_error(paste("Multiple replacements not supported,",
                               "`pattern` must be a length 1 character vector"))
      }
      if (length(replacement) != 1) {
        validation_error(paste("Multiple replacements not supported,",
                               "`replacement` must be a length 1 character vector"))
      }

I'm about to submit a PR. But first, I would like to confirm some minor things: (1) does the test file update automatically when I run devtools::test()? (I can't test my changes right now), (2) is there any other test or change I should make before submitting the PR?, (3) on r/R/dplyr-funcs-doc.R I wrote "not supported yet". Will this feature be implemented in the future or should I change it to "not supported"?

Component(s)

R