handlers() gained argument 'append'

Author: HenrikBengtsson

NEWS

@@ -1,12 +1,14 @@
 Package: progressr
 ==================
 
-Version: 0.2.1-9000 [2020-01-12]
+Version: 0.2.1-9000 [2020-01-20]
 
 NEW FEATURES:
 
  * progressor() gained offset and slope arguments 'a' and 'b', and functional
    argument 'transform'.
+
+ * handlers() gained argument 'append' to make it easier to append handlers.
 
 BUG FIXES:
 

R/handlers.R

@@ -5,6 +5,9 @@
 #' If this vector is empty, then an empty set of progression handlers will
 #' be set.
 #'
+#' @param append (logial) If FALSE, the specified progression handlers replace
+#' the current ones, otherwise appended to them.
+#'
 #' @param on_missing (character) If `"error"`, an error is thrown if one of
 #' the progression handlers does not exists.  If `"warning"`, a warning
 #' is produces and the missing handlers is ignored.  If `"ignore"`, the
@@ -24,7 +27,7 @@
 #' @example incl/handlers.R
 #'
 #' @export
-handlers <- function(..., on_missing = c("error", "warning", "ignore"), default = txtprogressbar_handler) {
+handlers <- function(..., append = FALSE, on_missing = c("error", "warning", "ignore"), default = txtprogressbar_handler) {
   args <- list(...)
 
   ## Get the current set of progression handlers?
@@ -82,5 +85,10 @@ handlers <- function(..., on_missing = c("error", "warning", "ignore"), default
   keep <- vapply(handlers, FUN = is.function, FUN.VALUE = FALSE)
   handlers <- handlers[keep]
 
+  if (append) {
+    current <- getOption("progressr.handlers", list())
+    if (length(current) > 0L) handlers <- c(current, handlers)
+  }
+
   options(progressr.handlers = handlers)[[1]]
 }

incl/with_progress.R

@@ -40,14 +40,13 @@ if (requireNamespace("beepr", quietly = TRUE)) {
 
 ## Progress reported via customied utils::txtProgressBar, beepr::beep,
 ## and notifier::notify, if available.
-handlers <- list(txtprogressbar_handler(style = 3L))
+handlers(txtprogressbar_handler(style = 3L))
 if (requireNamespace("beepr", quietly = TRUE)) {
-  handlers <- c(handlers, list(beepr_handler()))
+  handlers("beepr", append = TRUE)
 }
 if (requireNamespace("notifier", quietly = TRUE)) {
-  handlers <- c(handlers, list(notifier_handler(times = 3L, interval = 0.1)))
+  handlers(notifier_handler(times = 3L, interval = 0.1), append = TRUE)
 }
-handlers(handlers)
 
 with_progress({
   y <- slow_sum(1:30)