Assert function is variadic — assert_function_variadic • assertions

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)
})
#> Error in eval(expr, envir) : 
#>   'my_fun_no_dots' must accept variable arguments via ...