Assert that an object is a single whole number used as a count

Checks that x is a single non-negative whole number (0, 1, 2, ...). Doubles with no fractional part (such as 3) are accepted, as are integers.

Usage

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

Arguments

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.

Value

The input x, invisibly.

Examples

assert_scalar_count(3)
assert_scalar_count(0L)