check_exclusive: Check that arguments are mutually exclusive

In hadley/rlang: Functions for Base Types and Core R and 'Tidyverse' Features

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)

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.

Value

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

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()

hadley/rlang documentation built on April 24, 2024, 1:05 a.m.