R/options.R

In withr: Run Code 'With' Temporarily Modified Global State

#' @include with_.R

# options --------------------------------------------------------------------

get_options <- function(new_options) {
  do.call(options, as.list(names(new_options)))
}
set_options <- function(new_options) {
  do.call(options, as.list(new_options))
}
reset_options <- function(old_options) {
  options(old_options)
}

#' Options
#'
#' Temporarily change global options.
#'
#' @template with
#' @param new,.new `[named list]`\cr New options and their values
#' @param ... Additional options and their values
#' @inheritParams with_collate
#' @seealso [options()]
#' @examples
#' # number of significant digits to print
#' getOption("digits")
#' # modify temporarily the number of significant digits to print
#' with_options(list(digits = 3), getOption("digits"))
#' with_options(list(digits = 3), print(pi))
#'
#' # modify temporarily the character to be used as the decimal point
#' getOption("digits")
#' with_options(list(OutDec = ","), print(pi))
#'
#' # modify temporarily multiple options
#' with_options(list(OutDec = ",", digits = 3), print(pi))
#'
#' # modify, within the scope of the function, the number of
#' # significant digits to print
#' print_3_digits <- function(x) {
#'   # assign 3 to the option "digits" for the rest of this function
#'   # after the function exits, the option will return to its previous
#'   # value
#'   local_options(list(digits = 3))
#'   print(x)
#' }
#'
#' print_3_digits(pi)  # returns 3.14
#' print(pi)           # returns 3.141593

#' @export
with_options <- with_(
  set_options,
  reset_options
)

#' @rdname with_options
#' @export
local_options <- local_(
  set_options,
  reset_options,
  get = get_options,
  dots = TRUE
)