Assert that a single value belongs to a set — assert_value_in

Checks that x is a single value (length 1) equal to one of allowed_values. The scalar counterpart of assert_values_in_set(), which checks every element of a vector.

Usage

assert_value_in_set(
  x,
  allowed_values,
  null_ok = FALSE,
  arg = rlang::caller_arg(x),
  call = rlang::caller_env()
)

Arguments

x: Object to check.
allowed_values: Vector of permitted values.
null_ok: Single logical. If TRUE, a NULL value passes the check without error. Use this for optional arguments that default to NULL. Defaults to FALSE, so NULL is rejected unless you opt in.
arg: Name used to refer to x in error messages. Defaults to the name of the expression passed as x.
call: Environment used as the error's call context. Defaults to the calling function, so errors point at the user's code.

Value

The input x, invisibly.

Examples

assert_value_in_set("b", allowed_values = c("a", "b", "c"))