Ignore missing names

NEWS.md

@@ -6,6 +6,8 @@
 * `vars_select()` and `vars_rename()` now correctly support unquoting
   character vectors that have names.
 
+* `vars_select()` now ignores missing variables.
+
 
 # tidyselect 0.2.2
 

R/utils.R

@@ -69,3 +69,11 @@ is_character <- function(x, n = NULL) {
 
   TRUE
 }
+
+are_name <- function(nms) {
+  if (!is_character(nms)) {
+    abort("Expected a character vector")
+  }
+
+  nms == "" | is.na(nms)
+}

R/vars-select.R

@@ -211,14 +211,16 @@ is_concat_lang <- function(quo) {
 vars_select_eval <- function(vars, quos) {
   scoped_vars(vars)
 
+  # Peek validated variables
+  vars <- peek_vars()
+
   # Overscope `c`, `:` and `-` with versions that handle strings
   data_helpers <- list(`:` = vars_colon, `-` = vars_minus, `c` = vars_c)
   overscope_top <- new_environment(data_helpers)
 
   # Symbols and calls to `:` and `c()` are evaluated with data in scope
   is_helper <- map_lgl(quos, quo_is_helper)
   data <- set_names(as.list(seq_along(vars)), vars)
-  data <- data[!names(data) == ""]
   overscope <- env_bury(overscope_top, !!! data)
 
   overscope <- new_overscope(overscope, overscope_top)

R/vars.R

@@ -69,7 +69,9 @@
 #' }
 #' fn(starts_with("r"))
 poke_vars <- function(vars) {
-  stopifnot(is_character(vars) || is_null(vars))
+  if (!is_null(vars)) {
+    vars <- vars_validate(vars)
+  }
 
   old <- vars_env$selected
   vars_env$selected <- vars
@@ -109,4 +111,21 @@ has_vars <- function() {
   !is_null(vars_env$selected)
 }
 
+vars_validate <- function(vars) {
+  if (!is_character(vars)) {
+    abort("`vars` must be a character vector")
+  }
+
+  are_name <- are_name(vars)
+  if (any(!are_name)) {
+    # Propagate `type` attribute when subsetting. A proper S3 class
+    # might be better.
+    type <- attr(vars, "type")
+    vars <- vars[!are_name]
+    attr(vars, "type") <- type
+  }
+
+  vars
+}
+
 vars_env <- new_environment()

tests/testthat/test-vars-pull.R

@@ -34,3 +34,8 @@ test_that("errors for bad inputs", {
     fixed = TRUE
   )
 })
+
+test_that("can pull variables with missing elements", {
+  expect_identical(vars_pull(c("a", ""), a), "a")
+  expect_identical(vars_pull(c("a", NA), a), "a")
+})

tests/testthat/test-vars-select.R

@@ -42,6 +42,7 @@ test_that("symbol overscope works with parenthesised expressions", {
 
 test_that("can select with unnamed elements", {
   expect_identical(vars_select(c("a", ""), a), c(a = "a"))
+  expect_identical(vars_select(c("a", NA), a), c(a = "a"))
 })
 
 test_that("can customise error messages", {

tests/testthat/test-vars.R

@@ -31,3 +31,11 @@ test_that("has_vars() detects variables", {
   scoped_vars(letters)
   expect_true(has_vars())
 })
+
+test_that("Missing names are ignored", {
+  scoped_vars(c("foo", NA))
+  expect_identical(peek_vars(), "foo")
+
+  scoped_vars(c("bar", ""))
+  expect_identical(peek_vars(), "bar")
+})