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
andarg
isNULL
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)
. WhenNULL
, 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.
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_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)))
#> Error in example_fun(quos(USUBJID, PARAMCD)) :
#> Each element of the list in argument `by_vars` must be class/type
#> <symbol>.
#> ℹ But, element 1 is a <quosure> object, and element 2 is a <quosure> object
try(example_fun(c("USUBJID", "PARAMCD", "VISIT")))
#> Error in example_fun(c("USUBJID", "PARAMCD", "VISIT")) :
#> Argument `by_vars` must be class <list>, but is a character vector.
try(example_fun(exprs(USUBJID, toupper(PARAMCD), desc(AVAL))))
#> Error in example_fun(exprs(USUBJID, toupper(PARAMCD), desc(AVAL))) :
#> Each element of the list in argument `by_vars` must be class/type
#> <symbol>.
#> ℹ But, element 2 is a call, and element 3 is a call
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)))
#> Error in example_fun_name(exprs(APERSDT = APxxSDT, APxxEDT)) :
#> All elements of `by_vars` argument must be named.
#> ℹ The indices of the unnamed elements are 2