R: Is an Argument a Variable-Value List?

assert_varval_list {admiraldev}

R Documentation

Is an Argument a Variable-Value List?

Description

Checks if the argument is a list of expressions where the expressions are variable-value pairs. The value can be a symbol, a string, a numeric, an expression, or NA.

Usage

assert_varval_list(
  arg,
  required_elements = NULL,
  accept_expr = TRUE,
  accept_var = FALSE,
  optional = FALSE,
  arg_name = rlang::caller_arg(arg),
  message = NULL,
  class = "assert_varval_list",
  call = parent.frame()
)

Arguments

`arg`	A function argument to be checked
`required_elements`	A `character` vector of names that must be present in `arg`
`accept_expr`	Should expressions on the right hand side be accepted?
`accept_var`	Should unnamed variable names (e.g. `exprs(USUBJID)`) on the right hand side be accepted?
`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 variable-value expressions. Otherwise, the input it returned invisibly.

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_vars()

Examples

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

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

try(example_fun(exprs("AE", DTSEQ = AESEQ)))