Deprecate extraction_operator_linter()

closes #1485

Author: IndrajeetPatil

NEWS.md

@@ -12,6 +12,7 @@
    + Helper `with_defaults()`.
 * `all_linters()` has signature `all_linters(..., packages)` rather than `all_linters(packages, ...)` (#2332, @MichaelChirico). This forces `packages=` to be supplied by name and will break users who rely on supplying `packages=` positionally, of which we found none searching GitHub.
 * Adjusted various lint messages for consistency in readability (#1330, @MichaelChirico). In general, we favor lint messages to be phrased like "Action, reason" to but the "what" piece of the message front-and-center. This may be a breaking change for code that tests the specific phrasing of lints.
+* `extraction_operator_linter()` is deprecated. Although switching from `$` to `[[` has microoptimization benefits, it can lead to non-idiomatic code in many contexts (e.g. R6 classes, Shiny applications, etc.) (@IndrajeetPatil).
 
 ## Bug fixes
 

R/extraction_operator_linter.R

@@ -51,6 +51,13 @@
 #' @seealso [linters] for a complete list of linters available in lintr.
 #' @export
 extraction_operator_linter <- function() {
+  lintr_deprecated(
+    what = "extraction_operator_linter",
+    version = "3.2.0",
+    type = "Linter",
+    signal = "warning"
+  )
+
   constant_nodes_in_brackets <- paste0("self::", c("expr", "OP-PLUS", "NUM_CONST", "STR_CONST"))
   xpath <- glue("
   //OP-DOLLAR[not(preceding-sibling::expr[1]/SYMBOL[text() = 'self' or text() = '.self'])]

tests/testthat/test-extraction_operator_linter.R

@@ -1,5 +1,14 @@
+test_that("extraction_operator_linter generates deprecation warning", {
+  expect_warning(
+    extraction_operator_linter(),
+    rex::rex("Linter extraction_operator_linter was deprecated")
+  )
+})
+
 test_that("extraction_operator_linter skips allowed usages", {
-  linter <- extraction_operator_linter()
+  expect_warning({
+    linter <- extraction_operator_linter()
+  })
 
   expect_lint("x[[1]]", NULL, linter)
   expect_lint("x[-1]", NULL, linter)
@@ -10,7 +19,9 @@ test_that("extraction_operator_linter skips allowed usages", {
 })
 
 test_that("extraction_operator_linter blocks disallowed usages", {
-  linter <- extraction_operator_linter()
+  expect_warning({
+    linter <- extraction_operator_linter()
+  })
   msg_b <- rex::escape("Use `[[` instead of `[` to extract an element.")
   msg_d <- rex::escape("Use `[[` instead of `$` to extract an element.")