R/extract_dots.R

In rando: Context Aware Random Numbers

#' @name extract_dots
#'
#' @title Extract the ellipsis inside a function
#'
#' @description
#' Allow the named entries in `...` to be used easily within a
#' function by attaching them to the function's environment
#'
#' @return
#' No return value, called for it's side effect
#'
#' @examples
#'
#' f <- function(...) {
#'   a + b
#' }
#'
#'\dontrun{
#' # Throws an error because a and b are trapped inside `...`
#'  f(a = 1, b = 2)
#' }
#'
#' f <- function(...) {
#'   extract_dots()
#'   a + b
#' }
#' f(a = 1, b = 2)
#'
#' @export
extract_dots <- function() {
  .pcall <- match.call(sys.function(sys.parent()),
    sys.call(sys.parent()),
    expand.dots = F,
    envir = parent.frame(2L)
  )
  dots <- .pcall[["..."]]
  dots <- dots[names(dots) != ""]
  list2env(lapply(dots, eval, parent.frame(2)), parent.frame())
}