docs(news): Add news item

NAMESPACE

@@ -19,6 +19,7 @@ S3method("[[",shinyoutput)
 S3method("[[<-",reactivevalues)
 S3method("[[<-",shinyoutput)
 S3method("names<-",reactivevalues)
+S3method(as.list,Map)
 S3method(as.list,reactivevalues)
 S3method(as.shiny.appobj,character)
 S3method(as.shiny.appobj,list)
@@ -43,6 +44,7 @@ S3method(bindEvent,reactiveExpr)
 S3method(bindEvent,shiny.render.function)
 S3method(format,reactiveExpr)
 S3method(format,reactiveVal)
+S3method(length,Map)
 S3method(names,reactivevalues)
 S3method(print,reactive)
 S3method(print,reactivevalues)

NEWS.md

@@ -10,6 +10,8 @@
 
 * Added a new `ExtendedTask` abstraction, for long-running asynchronous tasks that you don't want to block the rest of the app, or even the rest of the session. Designed to be used with new `bslib::input_task_button()` and `bslib::bind_task_button()` functions that help give user feedback and prevent extra button clicks. (#3958)
 
+* The `shiny.error` will now pass the error condition object to a handler function if the handler takes an `error` argument. (#3987)
+
 ## Bug fixes
 
 * Notifications are now constrained to the width of the viewport for window widths smaller the default notification panel size. (#3949)

R/map.R

@@ -48,9 +48,12 @@ Map <- R6Class(
   )
 )
 
+#' @export
 as.list.Map <- function(x, ...) {
   x$values()
 }
+
+#' @export
 length.Map <- function(x) {
   x$size()
 }

R/shiny-options.R

@@ -80,7 +80,10 @@ getShinyOption <- function(name, default = NULL) {
 #'   [shinyDeprecated()] for more information.}
 #' \item{shiny.error (defaults to `NULL`)}{This can be a function which is called when an error
 #'   occurs. For example, `options(shiny.error=recover)` will result a
-#'   the debugger prompt when an error occurs.}
+#'   the debugger prompt when an error occurs. If the function takes an `error`
+#'   argument, it will be called with the error object. For example,
+#'   `options(shiny.error = function(error) { })` will receive the error
+#'   condition object when an error occurs.}
 #' \item{shiny.fullstacktrace (defaults to `FALSE`)}{Controls whether "pretty" (`FALSE`) or full
 #'   stack traces (`TRUE`) are dumped to the console when errors occur during Shiny app execution.
 #'   Pretty stack traces attempt to only show user-supplied code, but this pruning can't always

R/shiny.R

@@ -16,8 +16,7 @@ NULL
 #'
 #' @name shiny-package
 #' @aliases shiny
-#' @docType package
-NULL
+"_PACKAGE"
 
 createUniqueId <- function(bytes, prefix = "", suffix = "") {
   withPrivateSeed({

R/utils.R

@@ -488,7 +488,13 @@ shinyCallingHandlers <- function(expr) {
         return()
 
       handle <- getOption('shiny.error')
-      if (is.function(handle)) handle()
+      if (is.function(handle)) {
+        if ("error" %in% names(formals(handle))) {
+          handle(error = e)
+        } else {
+          handle()
+        }
+      }
     }
   )
 }

man/memoryCache.Rd

@@ -17,7 +17,7 @@ memoryCache(
 \arguments{
 \item{max_size}{Maximum size of the cache, in bytes. If the cache exceeds
 this size, cached objects will be removed according to the value of the
-\code{evict}. Use \code{Inf} for no size limit. The default is 1 gigabyte.}
+\code{evict}. Use \code{Inf} for no size limit. The default is 512 megabytes.}
 
 \item{max_age}{Maximum age of files in cache before they are evicted, in
 seconds. Use \code{Inf} for no age limit.}

man/plotPNG.Rd

@@ -41,7 +41,7 @@ set to \code{FALSE}), then use \code{\link[ragg:agg_png]{ragg::agg_png()}}.
 \item If a quartz device is available (i.e., \code{capabilities("aqua")} is
 \code{TRUE}), then use \code{png(type = "quartz")}.
 \item If the Cairo package is installed (and the \code{shiny.usecairo} option
-is not set to \code{FALSE}), then use \code{\link[Cairo:CairoPNG]{Cairo::CairoPNG()}}.
+is not set to \code{FALSE}), then use \code{\link[Cairo:Cairo]{Cairo::CairoPNG()}}.
 \item Otherwise, use \code{\link[grDevices:png]{grDevices::png()}}. In this case, Linux and Windows
 may not antialias some point shapes, resulting in poor quality output.
 }

man/shinyOptions.Rd

@@ -59,7 +59,10 @@ deprecated functions in Shiny will be printed. See
 \code{\link[=shinyDeprecated]{shinyDeprecated()}} for more information.}
 \item{shiny.error (defaults to \code{NULL})}{This can be a function which is called when an error
 occurs. For example, \code{options(shiny.error=recover)} will result a
-the debugger prompt when an error occurs.}
+the debugger prompt when an error occurs. If the function takes an \code{error}
+argument, it will be called with the error object. For example,
+\code{options(shiny.error = function(error) { })} will receive the error
+condition object when an error occurs.}
 \item{shiny.fullstacktrace (defaults to \code{FALSE})}{Controls whether "pretty" (\code{FALSE}) or full
 stack traces (\code{TRUE}) are dumped to the console when errors occur during Shiny app execution.
 Pretty stack traces attempt to only show user-supplied code, but this pruning can't always

tests/testthat/test-stacks.R

@@ -194,6 +194,17 @@ test_that("shiny.error", {
   expect_null(caught)
 })
 
+test_that("shiny.error passes the error condition to the handler", {
+  caught <- NULL
+  op <- options(shiny.error = function(error) { caught <<- error })
+  on.exit(options(op))
+
+  # Regular errors can be handled by shiny.error
+  try(shiny:::shinyCallingHandlers(stop("boom")), silent = TRUE)
+  expect_equal(conditionMessage(caught), "boom")
+  expect_s3_class(caught, "error")
+})
+
 test_that("chained silent errors aren't intercepted (tidyverse/dplyr#5552)", {
   withr::local_options(
     shiny.error = function() caught <<- TRUE