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Check Supplied Argument

Source: R/arg_supplied.R
arg_supplied.Rd

Checks whether an argument with no default value was supplied. An error will be thrown if rlang::is_missing(x) is TRUE, i.e., if an argument with no default is omitted from a function call.

Usage

arg_supplied(x, .arg = rlang::caller_arg(x), .msg = NULL, .call)

Arguments

x

the argument to be checked

.arg

the name of the argument supplied to x to appear in error messages. The default is to extract the argument's name using rlang::caller_arg(). Ignored if .msg is supplied.

.msg

an optional alternative message to display if an error is thrown instead of the default message.

.call

the execution environment of a currently running function, e.g. .call = rlang::current_env(). The corresponding function call is retrieved and mentioned in error messages as the source of the error. Passed to err(). Set to NULL to omit call information. The default is to search along the call stack for the first user-facing function in another package, if any.

Value

Returns NULL invisibly if an error is not thrown.

See also

arg_non_null(), arg_no_NA(), rlang::is_missing(), rlang::check_required()

Examples

f <- function(z) {
  arg_supplied(z)
}

try(f(1)) ## No error: argument supplied
try(f())  ## Error!
#> Error : An argument to `z` must be supplied.

# Will not throw for NULL or default arguments
try(f(NULL)) ## No error: argument supplied

f2 <- function(z = NULL) {
  arg_supplied(z)
}

try(f2()) ## No error; default provided