Add a names<- method for vctrs_rcrd

This is a no-op for `NULL` names, but otherwise errors. We should reconsider this in the future once we are ready to try and support names on rcrds, but for now this prevents `vec_set_names()` from corrupting rcrd types.

NAMESPACE

@@ -49,6 +49,7 @@ S3method("length<-",vctrs_rcrd)
 S3method("length<-",vctrs_vctr)
 S3method("levels<-",vctrs_sclr)
 S3method("levels<-",vctrs_vctr)
+S3method("names<-",vctrs_rcrd)
 S3method("names<-",vctrs_sclr)
 S3method("names<-",vctrs_vctr)
 S3method("|",vctrs_vctr)

NEWS.md

@@ -1,5 +1,7 @@
 # vctrs (development version)
 
+* `vec_set_names()` no longer corrupts `vctrs_rcrd` types (#1419).
+
 * `vec_detect_complete()` now computes completeness for `vctrs_rcrd` types in
   the same way as data frames, which means that if any field is missing, the
   entire record is considered incomplete (#1386).

R/type-rcrd.R

@@ -50,6 +50,15 @@ names.vctrs_rcrd <- function(x) {
   NULL
 }
 
+#' @export
+`names<-.vctrs_rcrd` <- function(x, value) {
+  if (is_null(value)) {
+    x
+  } else {
+    abort("Can't assign names to a <vctrs_rcrd>.")
+  }
+}
+
 #' @export
 format.vctrs_rcrd <- function(x, ...) {
   if (inherits(x, "vctrs_foobar")) {

tests/testthat/test-type-rcrd.R

@@ -26,6 +26,28 @@ test_that("vec_proxy() transforms records to data frames", {
   )
 })
 
+# base methods ------------------------------------------------------------
+
+test_that("has no names", {
+  x <- new_rcrd(list(a = 1, b = 2L))
+
+  expect_null(names(x))
+  expect_null(vec_names(x))
+})
+
+test_that("removing names with `NULL` is a no-op (#1419)", {
+  x <- new_rcrd(list(a = 1, b = 2L))
+
+  expect_identical(`names<-`(x, NULL), x)
+  expect_identical(vec_set_names(x, NULL), x)
+})
+
+test_that("setting character names is an error (#1419)", {
+  x <- new_rcrd(list(a = 1, b = 2L))
+
+  expect_error(`names<-`(x, "x"), "Can't assign names")
+  expect_error(vec_set_names(x, "x"), "Can't assign names")
+})
 
 # coercion ----------------------------------------------------------------