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Check Character Argument

Source: R/arg_character.R
arg_character.Rd

Checks whether an argument is a character vector (arg_character()), a character scalar (arg_string()), or a factor (arg_factor()).

Usage

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

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

arg_factor(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.

Details

NA values in arg_string() will cause an error to be thrown.

See also

is.character(), is.factor(), rlang::is_string()

Examples

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

try(f("a")) # No error
try(f(c("a", "b"))) # Error: arg_string() requires scalar
#> Error : `z` must be a string.
try(f(NA)) # NAs not allowed for arg_string()
#> Error : `z` must be a string.