Assert that an object inherits from a class

Checks that x inherits from every class named in class, using inherits().

Usage

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

x: Object to check.
class: Character vector of one or more class names that x must inherit from.
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_class(Sys.Date(), "Date")