assert_list_of: Is an Argument a List of Objects of a Specific S3 Class or Type?

Description

Checks if an argument is a list of objects inheriting from the S3 class or type specified.

Usage

assert_list_of(
  arg,
  cls,
  named = FALSE,
  optional = TRUE,
  arg_name = rlang::caller_arg(arg),
  message = NULL,
  class = "assert_list_of",
  call = parent.frame()
)

Value

The function throws an error if arg is not a list or if arg is a list but its elements are not objects inheriting from class or of type class. Otherwise, the input is returned invisibly.

Arguments

arg

A function argument to be checked

cls

The S3 class or type to check for

named

If set to TRUE, an error is issued if not all elements of the list are named.

optional

Is the checked argument optional? If set to FALSE and arg is NULL then an error is thrown

arg_name

string indicating the label/symbol of the object being checked.

message

string passed to cli::cli_abort(message). When NULL, default messaging is used (see examples for default messages). "{arg_name}" can be used in messaging.

class

Subclass of the condition.

call

The execution environment of a currently running function, e.g. call = caller_env(). The corresponding function call is retrieved and mentioned in error messages as the source of the error.

You only need to supply call when throwing a condition from a helper function which wouldn't be relevant to mention in the message.

Can also be NULL or a defused function call to respectively not display any call or hard-code a code to display.

For more information about error calls, see Including function calls in error messages.

Checks for valid input and returns warning or errors messages: assert_atomic_vector(), assert_character_scalar(), assert_character_vector(), assert_data_frame(), assert_date_vector(), assert_expr(), assert_expr_list(), assert_filter_cond(), assert_function(), assert_integer_scalar(), assert_list_element(), assert_logical_scalar(), assert_named(), assert_numeric_vector(), assert_one_to_one(), assert_param_does_not_exist(), assert_s3_class(), assert_same_type(), assert_symbol(), assert_unit(), assert_vars(), assert_varval_list()

Examples

Run this code

example_fun <- function(list) {
  assert_list_of(list, "data.frame")
}

example_fun(list(mtcars, iris))

try(example_fun(list(letters, 1:10)))

try(example_fun(c(TRUE, FALSE)))

example_fun2 <- function(list) {
  assert_list_of(list, "numeric", named = TRUE)
}
try(example_fun2(list(1, 2, 3, d = 4)))

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