eval-walk.md
In tidyselect: Select from a Set of Strings

scalar boolean operators fail informatively

Code
  select_loc(letters2, starts_with("a") || ends_with("b"))
Condition
  Error in `select_loc()`:
  ! Can't use scalar `||` in selections.
  i Do you need `|` instead?
Code
  select_loc(letters2, starts_with("a") && ends_with("b"))
Condition
  Error in `select_loc()`:
  ! Can't use scalar `&&` in selections.
  i Do you need `&` instead?

can't use `*` and `^` in data context

Code
  select_loc(letters2, a * 2)
Condition
  Error in `select_loc()`:
  ! Can't use arithmetic operator `*` in selection context.
Code
  select_loc(letters2, a^2)
Condition
  Error in `select_loc()`:
  ! Can't use arithmetic operator `^` in selection context.

symbol lookup outside data informs caller about better practice

Code
  vars <- c("a", "b")
  select_loc(letters2, vars)
Condition
  Warning:
  Using an external vector in selections was deprecated in tidyselect 1.1.0.
  i Please use `all_of()` or `any_of()` instead.
    # Was:
    data %>% select(vars)

    # Now:
    data %>% select(all_of(vars))

  See <https://tidyselect.r-lib.org/reference/faq-external-vector.html>.
Output
  a b 
  1 2

can forbid use of predicates

Code
  select_loc(iris, where(is.factor), allow_predicates = FALSE)
Condition
  Error in `select_loc()`:
  ! This tidyselect interface doesn't support predicates.

selections provide informative errors

Code
  # Foreign errors during evaluation
  select_loc(iris, eval_tidy(foobar))
Condition
  Error in `select_loc()`:
  i In argument: `eval_tidy(foobar)`.
  Caused by error:
  ! object 'foobar' not found

use of .data is deprecated

Code
  x <- select_loc(x, .data$a)
Condition
  Warning:
  Use of .data in tidyselect expressions was deprecated in tidyselect 1.2.0.
  i Please use `"a"` instead of `.data$a`

Code
  x <- select_loc(x, .data[[var]])
Condition
  Warning:
  Use of .data in tidyselect expressions was deprecated in tidyselect 1.2.0.
  i Please use `all_of(var)` (or `any_of(var)`) instead of `.data[[var]]`

eval_walk() has informative messages

Code
  # Using a predicate without where() warns
  invisible(select_loc(iris, is_integer))
Condition
  Warning:
  Use of bare predicate functions was deprecated in tidyselect 1.1.0.
  i Please use wrap predicates in `where()` instead.
    # Was:
    data %>% select(is_integer)

    # Now:
    data %>% select(where(is_integer))
Code
  invisible(select_loc(iris, is.numeric))
Condition
  Warning:
  Use of bare predicate functions was deprecated in tidyselect 1.1.0.
  i Please use wrap predicates in `where()` instead.
    # Was:
    data %>% select(is.numeric)

    # Now:
    data %>% select(where(is.numeric))
Code
  invisible(select_loc(iris, isTRUE))
Condition
  Warning:
  Use of bare predicate functions was deprecated in tidyselect 1.1.0.
  i Please use wrap predicates in `where()` instead.
    # Was:
    data %>% select(isTRUE)

    # Now:
    data %>% select(where(isTRUE))
Code
  # Warning is not repeated
  invisible(select_loc(iris, is_integer))
Condition
  Warning:
  Use of bare predicate functions was deprecated in tidyselect 1.1.0.
  i Please use wrap predicates in `where()` instead.
    # Was:
    data %>% select(is_integer)

    # Now:
    data %>% select(where(is_integer))
Code
  # formula shorthand must be wrapped
  (expect_error(select_loc(mtcars, ~ is.numeric(.x))))
Output
  <error/rlang_error>
  Error in `select_loc()`:
  ! Formula shorthand must be wrapped in `where()`.

    # Bad
    data %>% select(~is.numeric(.x))

    # Good
    data %>% select(where(~is.numeric(.x)))
Code
  (expect_error(select_loc(mtcars, ~ is.numeric(.x) || is.factor(.x) ||
    is.character(.x))))
Output
  <error/rlang_error>
  Error in `select_loc()`:
  ! Formula shorthand must be wrapped in `where()`.

    # Bad
    data %>% select(~is.numeric(.x) || is.factor(.x) || is.character(.x))

    # Good
    data %>% select(where(~is.numeric(.x) || is.factor(.x) || is.character(.x)))
Code
  (expect_error(select_loc(mtcars, ~ is.numeric(.x) || is.factor(.x) ||
    is.character(.x) || is.numeric(.x) || is.factor(.x) || is.character(.x))))
Output
  <error/rlang_error>
  Error in `select_loc()`:
  ! Formula shorthand must be wrapped in `where()`.

    # Bad
    data %>% select(~...)

    # Good
    data %>% select(where(~...))
Code
  (expect_error(select_loc(mtcars, .data$"foo")))
Output
  <error/rlang_error>
  Error in `select_loc()`:
  ! The RHS of `.data$rhs` must be a symbol.

can forbid empty selection

Code
  ensure_named(integer(), allow_empty = FALSE)
Condition
  Error:
  ! Must select at least one item.
Code
  ensure_named(integer(), allow_empty = FALSE, allow_rename = FALSE)
Condition
  Error:
  ! Must select at least one item.