Preserve condition object in a miraiError

NEWS.md

@@ -12,6 +12,7 @@
 * Upgrades `stop_mirai()` to cancel remote mirai tasks when using the new dispatcher, returning a logical value indicating whether cancellation was successful.
 * Adds `stop_daemon()` to reduce the number of connected daemons (without interrupting any executing tasks).
 * `daemon()` gains the new argument 'dispatcher', which should be set to `TRUE` when connecting to dispatcher and `FALSE` when connecting directly to host.
+* A 'miraiError' now preserves the original condition object. This means that `rlang::abort()` custom metadata may now be accessed using `$` on the 'miraiError' (thanks @James-G-Hill #173).
 
 #### Updates
 

R/mirai.R

@@ -595,12 +595,12 @@ print.miraiInterrupt <- function(x, ...) {
 #' @export
 #'
 `$.miraiError` <- function(x, name)
-  attr(x, name, exact = FALSE)
+  attr(x, name, exact = TRUE)
 
 #' @exportS3Method utils::.DollarNames
 #'
 .DollarNames.miraiError <- function(x, pattern = "")
-  if (startsWith("stack.trace", pattern)) "stack.trace" else character()
+  grep(pattern, names(attributes(x)), value = TRUE, fixed = TRUE)
 
 # internals --------------------------------------------------------------------
 
@@ -628,7 +628,7 @@ mk_mirai_error <- function(e, sc) {
   msg <- if (is.null(call) || call == "eval(._mirai_.[[\".expr\"]], envir = ._mirai_., enclos = .GlobalEnv)")
     sprintf("Error: %s", .subset2(e, "message")) else
       sprintf("Error in %s: %s", call, .subset2(e, "message"))
-  cat(sprintf("%s\n", msg), file = stderr())
+  attributes(msg) <- e
   idx <- which(as.logical(lapply(sc, identical, quote(eval(._mirai_.[[".expr"]], envir = ._mirai_., enclos = .GlobalEnv)))))
   sc <- sc[(length(sc) - 1L):(idx + 1L)]
   if (sc[[1L]][[1L]] == ".handleSimpleError")

tests/tests.R

@@ -41,7 +41,7 @@ test_print(r)
 test_true(is_mirai_error(r <- `class<-`("Error in: testing\n", c("miraiError", "errorValue", "try-error"))))
 test_print(r)
 test_null(r$stack.trace)
-test_equal(mirai:::.DollarNames.miraiError(NULL, "s"), "stack.trace")
+test_equal(mirai:::.DollarNames.miraiError(r, "c"), "class")
 test_true(mirai:::is.promising.mirai())
 test_error(everywhere({}), "not found")
 test_null(nextstream())