R/cat_fact.R

In sckott/catfact: Get HTTP Cat Status Images

#' get a cat fact
#'
#' @export
#' @param max_length (integer) limits the length of the facts returned
#' @param ... curl options passed on to `httr::GET`
#' @return a cat fact in a list
#' @examples \dontrun{
#' cat_fact()
#' cat_fact(40)
#' cat_fact(80)
#' cat_fact('asdf') # invalid max_length returns nothing
#' }
cat_fact <- function(max_length = NULL, ...) {
  assert(max_length, c('integer', 'numeric'))

  args <- cp(list(max_length = max_length))
  res <- httr::GET("https://catfact.ninja/fact", query = args, ...)
  httr::stop_for_status(res)
  httr::content(res, as = "parsed", encoding = "UTF-8")
}

cp <- function(x) Filter(Negate(is.null), x)

assert <- function(x, y) {
  if (!is.null(x)) {
    if (!class(x)[1L] %in% y) {
      stop(deparse(substitute(x)), " must be of class ",
           paste0(y, collapse = ", "), call. = FALSE)
    }
  }
}