Is an Element of a List of Lists/Classes Fulfilling a Condition?

Checks if the elements of a list of named lists/classes fulfill a certain condition. If not, an error is issued and all elements of the list not fulfilling the condition are listed.

Usage

assert_list_element(
  list,
  element,
  condition,
  message_text,
  arg_name = rlang::caller_arg(list),
  message = NULL,
  class = "assert_list_element",
  call = parent.frame(),
  ...
)

Arguments

list

A list to be checked A list of named lists or classes is expected.

element

The name of an element of the lists/classes A character scalar is expected.

condition

Condition to be fulfilled The condition is evaluated for each element of the list. The element of the lists/classes can be referred to by its name, e.g., censor == 0 to check the censor field of a class.

message_text

Text to be displayed in the error message above the listing of values that do not meet the condition. The text should describe the condition to be fulfilled, e.g., "Error in {arg_name}: the censor values must be zero.". If message argument is specified, that text will be displayed and message_text is ignored.

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.

...

Objects required to evaluate the condition If the condition contains objects apart from the element, they have to be passed to the function. See the second example below.

Value

An error if the condition is not met. The input otherwise.

See also

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_of(), 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()