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Is an Argument a Variable-Value List?

Source: R/assertions.R
assert_varval_list.Rd

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
)

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.

Value

The function throws an error if arg is not a list of variable-value 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_list(), 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()

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)))
#> Error in assert_varval_list(vars) : 
#>   `vars` must be a named list of expressions where each element is a symbol, character scalar, numeric scalar, an expression, or `NA` but it is a list
#> ℹ To create a list of expressions use `exprs()`