rlang (version 1.3.0)

stop_input_type: Throw a type mismatch error

Description

stop_input_type() throws an error when an argument has the wrong type, producing a friendly error message that includes the expected type and the actual type of the input.

Usage

stop_input_type(
  x,
  what,
  ...,
  allow_na = FALSE,
  allow_null = FALSE,
  show_value = TRUE,
  arg = caller_arg(x),
  call = caller_env()
)

Value

Throws an error, does not return.

Arguments

x

The object that does not conform to what. Its "friendly type" is used in the error message.

what

The friendly expected type as a string. Can be a character vector of expected types, in which case the error message mentions all of them in an "or" enumeration.

...

Additional arguments passed to abort().

allow_na

If TRUE, an NA description is appended to what in the error message.

allow_null

If TRUE, a NULL description is appended to what in the error message.

show_value

Whether to show the actual value in the error message.

arg

An argument name as a string. This argument will be mentioned in error messages as the input that is at the origin of a problem.

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.

See Also

Other input checkers: check_data_frame(), check_type_number, check_type_scalar

Examples

check_character <- function(
  x,
  ...,
  allow_null = FALSE,
  arg = caller_arg(x),
  call = caller_env()
) {
  if (!missing(x)) {
    if (is_character(x)) {
      return(invisible(NULL))
    }
    if (allow_null && is_null(x)) {
      return(invisible(NULL))
    }
  }

  stop_input_type(
    x,
    "a character vector",
    ...,
    allow_null = allow_null,
    arg = arg,
    call = call
  )
}

# Succeeds
check_character(letters)

# Fails
try(check_character(42))