BETA: It is now possible to signal absolute progress, e.g. p(step = 42) [#110]

Author: HenrikBengtsson

NEWS

@@ -25,6 +25,17 @@ NEW FEATURES:
  * Add handlers("rstudio") to report on progress in the RStudio Console via
    the RStudio Job interface.
 
+BETA FEATURES:
+
+ * As an alternative to specifying the relative amount of progress, say, 
+   p(amount = 2), it is now possible to also specify the absolute amount of
+   progress made this far, e.g. p(step = 42).  Argument 'amount' has not
+   effect when argument 'step' is specfied.  WARNING: Argument `step` should
+   only be used when in full control of the order when this progression
+   condition is signaled.  For example, it must not be signaled as one of many
+   parallel progress updates signaled concurrently, because we cannot guarantee
+   the order these progressions arrive.
+
 BUG FIXES:
 
  * In progressr 0.7.0, any attempt to use more than one progressor inside a

R/make_progression_handler.R

@@ -390,7 +390,11 @@ make_progression_handler <- function(name, reporter = list(), handler = NULL, en
           if (debug) message("- cannot 'update' handler, because it is not active")
           return(invisible(finished))
         }
-        if (debug) mstr(list(step=step, "p$amount"=p[["amount"]], max_steps=max_steps))
+        if (debug) mstr(list(step=step, "p$amount"=p[["amount"]], "p$step"=p[["step"]], max_steps=max_steps))
+        if (!is.null(p[["step"]])) {
+          ## Infer effective 'amount' from previous 'step' and p$step
+          p[["amount"]] <- p[["step"]] - step
+        }
         step <<- min(max(step + p[["amount"]], 0L), max_steps)
         stop_if_not(step >= 0L)
         msg <- conditionMessage(p)

R/progression.R

@@ -10,7 +10,11 @@
 #'
 #' @param amount (numeric) The total amount of progress made.
 #'
-#' @param step (character or integer) The step completed.
+#' @param step (numeric) The step completed. If specified, `amount` is ignored.
+#' _WARNING: Argument `step` should only be used when in full control of the
+#' order when this progression condition is signaled._ For example, it must not
+#' be signaled as one of many parallel progress updates signaled concurrently,
+#' because then we cannot guarantee the order these progressions arrive.
 #'
 #' @param time (POSIXct) A timestamp.
 #'