Apply a predicate check to each element of a vector

Apply a predicate check function to each element of a vector and throw an error if any element fails the check.

Usage

walk_check(.x, .f, ..., call = caller_env())

Arguments

.x

A list or atomic vector.

.f

A function or formula to apply to each element of .x (passed to as_function()). Must return a logical vector of all TRUE for no error to occur. Non-logical and NA values will trigger an error.

...

Additional arguments passed to cli_abort() which forwards unmatched arguments to abort().

call

The execution environment of a currently running function, e.g. caller_env(). The function will be mentioned in error messages as the source of the error. See the call argument of abort() for more information.

Value

.x invisibly if all checks pass, otherwise an error is thrown.

Details

walk_check() is designed to work with predicate functions, throwing an error indicating the element that fails the check. If you wish to use a function for .f that itself errors, pass contextual information to that function directly (e.g., using a shorthand anonymous function), as the error will be thrown from that function's context and won't have direct access to information from the caller such as ... and call.

See also

Other checks: array-type-checks, forbidden-value-checks, inheritance-checks, oop-checks, path-checks, property-checks, s3-type-checks, scalar-type-checks, scalar-value-checks, type-checks

Examples

x <- list(1, 2, "a")
walk_check(x, is.atomic)
walk_check(x, ~ length(.x) == 1L)
walk_check(x, is.numeric) |> try()
#> Error in eval(expr, envir) : 
#>   Check result for `.x[[3]]` is not TRUE.
walk_check(x, \(el) nchar(el) == 1L)

# Named elements are shown in the error.
x <- list(a = 1, b = 2, c = "a")
walk_check(x, is.numeric) |> try()
#> Error in eval(expr, envir) : 
#>   Check result for `.x[['c']]` (index: 3) is not TRUE.