assert_vars {admiraldev}

Is an Argument a List of Variables?

Description

Checks if an argument is a valid list of symbols (e.g., created by exprs())

Usage

assert_vars(arg, expect_names = FALSE, optional = FALSE)

Arguments

arg

A function argument to be checked

expect_names

If the argument is set to TRUE, it is checked if all variables are named, e.g., exprs(APERSDT = APxxSDT, APEREDT = APxxEDT).

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 symbols (e.g., created by exprs() and returns the input invisibly 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_list(), assert_expr(), assert_filter_cond(), assert_function(), 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_varval_list()

Examples

library(dplyr, warn.conflicts = FALSE)
library(rlang)

example_fun <- function(by_vars) {
  assert_vars(by_vars)
}

example_fun(exprs(USUBJID, PARAMCD))

try(example_fun(quos(USUBJID, PARAMCD)))

try(example_fun(c("USUBJID", "PARAMCD", "VISIT")))

try(example_fun(exprs(USUBJID, toupper(PARAMCD), desc(AVAL))))

example_fun_name <- function(by_vars) {
  assert_vars(by_vars, expect_names = TRUE)
}

example_fun_name(exprs(APERSDT = APxxSDT, APEREDT = APxxEDT))

try(example_fun_name(exprs(APERSDT = APxxSDT, APxxEDT)))