R: Is an Argument a List of Variables?

assert_vars {admiraldev}

R Documentation

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,
  arg_name = rlang::caller_arg(arg),
  message = NULL,
  class = "assert_vars",
  call = parent.frame()
)

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
`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.

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.

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_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)))