R: Throw a type mismatch error

stop_input_type {rlang}

R Documentation

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()
)

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.

Value

Throws an error, does not return.

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))