Check that dots are empty

... can be inserted in a function signature to force users to fully name the details arguments. In this case, supplying data in ... is almost always a programming error. This function checks that ... is empty and fails otherwise.

check_dots_empty(
  env = caller_env(),
  error = NULL,
  call = caller_env(),
  action = abort
)

Arguments

env

Environment in which to look for ....

error

An optional error handler passed to try_fetch(). Use this e.g. to demote an error into a warning.

call

The execution environment of a currently running function, e.g. caller_env(). The function will be mentioned in error messages as the source of the error. See the call argument of abort() for more information.

action

Details

In packages, document ... with this standard tag:

 @inheritParams rlang::args_dots_empty

See also

Other dots checking functions: check_dots_unnamed(), check_dots_used()

Examples

f <- function(x, ..., foofy = 8) {
  check_dots_empty()
  x + foofy
}

# This fails because `foofy` can't be matched positionally
try(f(1, 4))
#> Error in f(1, 4) : `...` must be empty.
#> ✖ Problematic argument:
#> • ..1 = 4
#> ℹ Did you forget to name an argument?

# This fails because `foofy` can't be matched partially by name
try(f(1, foof = 4))
#> Error in f(1, foof = 4) : `...` must be empty.
#> ✖ Problematic argument:
#> • foof = 4

# Thanks to `...`, it must be matched exactly
f(1, foofy = 4)
#> [1] 5