assert_function_variadic: Assert function is variadic

In assertions: Simple Assertions for Beautiful and Customisable Error Messages

Assert function is variadic

Description

Assert that a function signature declares the ... argument (variadic arguments).

Usage

assert_function_variadic(
  x,
  msg = NULL,
  call = rlang::caller_env(),
  arg_name = NULL
)

Arguments

x	a function to check includes ... in its signature
msg	The error message thrown if the assertion fails (string)
call	Only relevant when pooling assertions into multi-assertion helper functions. See cli_abort for details.
arg_name	Advanced use only. Name of the argument passed (default: NULL, will automatically extract arg_name).

Value

invisible(TRUE) if function x declares ..., otherwise aborts with the error message specified by msg

Examples

my_fun <- function(x, ...) x
assert_function_variadic(my_fun)

try({
  my_fun_no_dots <- function(x) x
  assert_function_variadic(my_fun_no_dots)
})

assertions documentation built on Feb. 13, 2026, 5:06 p.m.