sy <- base::summary
nu <- function(x) length(unique(x))
su <- function(x) sort(unique(x))
oer <- function() options(error = utils::recover)
oet <- function() options(error = traceback)
oen <- function() options(error = NULL)
colgrep <- function(pat) grep(pat, grDevices::colors(), value = TRUE)
coldisplay <- function(cols) {
  cols <- colgrep(cols)
  x <- ceiling(sqrt(length(cols)))
  graphics::plot(rep(1:x, each = x)*2, rep(1:x, x), pch = 19, cex = 5, col = cols)
  graphics::text(rep(1:x, each = x)*2, rep(1:x, x), cols, pos = c(1,3),
    col = grDevices::adjustcolor(cols, .7, .7,.7,.7), pch = 0.7)
}


print.command <- function (cmd) {
  default.args <- attr(cmd, "default.args")
  if (length(default.args) == 0L) default.args <- list()
  res <- do.call(cmd, default.args, envir = parent.frame(2))
  if (attr(cmd, "print_result")) print(res)
  invisible(NULL)
}


make_command <- function(x, ..., print = TRUE) {
  class(x) <- c("command", class(x))
  attr(x, "default.args") <- list(...)
  attr(x, "print_result") <- print
  x
}


ls <- make_command(ls)
oer <- make_command(oer, print = FALSE)
oet <- make_command(oet, print = FALSE)
oen <- make_command(oen, print = FALSE)
lf <- make_command(list.files)
getwd <- make_command(getwd)

cat("My own functions:
  sy nu su ls lf getwd oer oet oen
  colgrep coldisplay make_command\n")
cat("Commands which don't need brackets:
  ls lf getwd oer oet oen\n\n")