Ensure an argument meets expectations

stabilize_arg() is used by other functions such as stabilize_int(). Use stabilize_arg() if the type-specific functions will not work for your use case, but you would still like to check things like size or whether the argument is NULL.

stabilize_arg_scalar() is optimized to check for length-1 vectors.

Usage

stabilize_arg(
  x,
  ...,
  allow_null = TRUE,
  allow_na = TRUE,
  min_size = NULL,
  max_size = NULL,
  x_arg = caller_arg(x),
  call = caller_env(),
  x_class = object_type(x)
)

stabilize_arg_scalar(
  x,
  ...,
  allow_null = TRUE,
  allow_zero_length = TRUE,
  allow_na = TRUE,
  x_arg = caller_arg(x),
  call = caller_env(),
  x_class = object_type(x)
)

Arguments

x

The argument to stabilize.

...

These dots are for future extensions and should be empty.

allow_null

Logical. Is NULL an acceptable value?

allow_na

Logical. Are NA values ok?

min_size

Integer. The minimum size of the object. Object size will be tested using vctrs::vec_size().

max_size

Integer. The maximum size of the object. Object size will be tested using vctrs::vec_size().

x_arg

Character. An argument name for x. The automatic value will work in most cases, or pass it through from higher-level functions to make error messages clearer in unexported functions.

call

The execution environment of the call. See the call argument of rlang::abort() for more information.

x_class

Character. The class name of x to use in error messages. Use this if you remove a special class from x before checking its coercion, but want the error message to match the original class.

allow_zero_length

Logical. Are zero-length vectors acceptable?

Value

x, unless one of the checks fails.

Examples

wrapper <- function(this_arg, ...) {
  stabilize_arg(this_arg, ...)
}
wrapper(1)
#> [1] 1
wrapper(NULL)
#> NULL
wrapper(NA)
#> [1] NA
try(wrapper(NULL, allow_null = FALSE))
#> Error in wrapper(NULL, allow_null = FALSE) : 
#>   `this_arg` must not be <NULL>.
try(wrapper(NA, allow_na = FALSE))
#> Error in wrapper(NA, allow_na = FALSE) : 
#>   `this_arg` must not contain NA values.
#> • NA locations: 1
try(wrapper(1, min_size = 2))
#> Error in wrapper(1, min_size = 2) : 
#>   `this_arg` must have size >= 2.
#> ✖ 1 is too small.
try(wrapper(1:10, max_size = 5))
#> Error in wrapper(1:10, max_size = 5) : 
#>   `this_arg` must have size <= 5.
#> ✖ 10 is too big.
stabilize_arg_scalar("a")
#> [1] "a"
stabilize_arg_scalar(1L)
#> [1] 1
try(stabilize_arg_scalar(1:10))
#> Error in eval(expr, envir, enclos) : 
#>   `1:10` must be a single <integer>.
#> ✖ `1:10` has 10 values.