Is an Argument a List of Expressions? — assert_expr_list • admiraldev

Checks if the argument is a list of expressions.

Usage

assert_expr_list(
  arg,
  required_elements = NULL,
  named = FALSE,
  optional = FALSE
)

Arguments

arg: A function argument to be checked
required_elements: A character vector of names that must be present in arg
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.

Value

The function throws an error if arg is not a list of expressions. Otherwise, the input it returned invisibly.

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_filter_cond(), assert_function_param(), assert_integer_scalar(), assert_list_element(), 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()

Examples

library(rlang)

example_fun <- function(vars) {
  assert_expr_list(vars)
}
example_fun(exprs(DTHDOM = "AE", DTHSEQ = AESEQ))

try(example_fun(exprs("AE", DTSEQ = AESEQ, !!list("a"))))
#> Error in assert_expr_list(vars) : 
#>   All elements of `vars` must be an expression.
#> vars[[3]] = `list("a")` is of type list