Assert that an object's names are unique — assert_unique

Checks that x has names (see assert_named()) and that no name is repeated.

Usage

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

x: Object to check.
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.

The input x, invisibly.

assert_unique_names(c(a = 1, b = 2))