rlang (version 1.1.0)

check_exclusive: Check that arguments are mutually exclusive

Description

check_exclusive() checks that only one argument is supplied out of a set of mutually exclusive arguments. An informative error is thrown if multiple arguments are supplied.

Usage

check_exclusive(..., .require = TRUE, .frame = caller_env(), .call = .frame)

Value

The supplied argument name as a string. If .require is FALSE and no argument is supplied, the empty string "" is returned.

Arguments

...

Function arguments.

.require

Whether at least one argument must be supplied.

.frame

Environment where the arguments in ... are defined.

.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.

Examples

f <- function(x, y) {
  switch(
    check_exclusive(x, y),
    x = message("`x` was supplied."),
    y = message("`y` was supplied.")
  )
}

# Supplying zero or multiple arguments is forbidden
try(f())
try(f(NULL, NULL))

# The user must supply one of the mutually exclusive arguments
f(NULL)
f(y = NULL)


# With `.require` you can allow zero arguments
f <- function(x, y) {
  switch(
    check_exclusive(x, y, .require = FALSE),
    x = message("`x` was supplied."),
    y = message("`y` was supplied."),
    message("No arguments were supplied")
  )
}
f()