Use rlang for error wrapping, if available

DESCRIPTION

@@ -32,6 +32,7 @@ Suggests:
     pander,
     parallel,
     R.utils,
+    rlang,
     rmarkdown,
     roxygen2,
     RPushbullet,

NEWS.md

@@ -7,6 +7,7 @@
 * `log_appender()`, `log_layout()` and `log_formatter()` now check that you are calling them with a function, and return the previously set value (#170, @hadley)
 * new function to return number of log indices (#194, @WurmPeter)
 * `appender_async` is now using `mirai` instead of a custom background process and queue system (#214, @hadley @shikokuchuo)
+* If `rlang` is installed, errors in `formatter_glue()` and `formatter_glue_safe()` get improved appearance
 
 ## Fixes
 

R/formatters.R

@@ -44,21 +44,13 @@ formatter_glue <- function(...,
                            .topenv = parent.frame()) {
   fail_on_missing_package("glue")
 
-  withCallingHandlers(
+  out <- wrap_glue(
     glue::glue(..., .envir = .topenv),
-    error = function(e) {
-      args <- paste0(capture.output(str(...)), collapse = "\n")
-
-      stop(paste0(
-        "`glue` failed in `formatter_glue` on:\n\n",
-        args,
-        "\n\nRaw error message:\n\n",
-        conditionMessage(e),
-        "\n\nPlease consider using another `log_formatter` or ",
-        "`skip_formatter` on strings with curly braces."
-      ))
-    }
+    inputs = list(...),
+    glue_fun = "glue",
+    logger_fun = "formatter_glue"
   )
+  as.character(out)
 }
 attr(formatter_glue, "generator") <- quote(formatter_glue())
 
@@ -75,24 +67,64 @@ formatter_glue_safe <- function(...,
                                 .topcall = sys.call(-1),
                                 .topenv = parent.frame()) {
   fail_on_missing_package("glue")
-  as.character(
-    tryCatch(
-      glue::glue_safe(..., .envir = .topenv),
-      error = function(e) {
-        stop(paste(
-          "`glue_safe` failed in `formatter_glue_safe` on:\n\n",
-          capture.output(str(...)),
+
+  out <- wrap_glue(
+    glue::glue_safe(..., .envir = .topenv),
+    inputs = list(...),
+    glue_fun = "glue_safe",
+    logger_fun = "formatter_glue_safe"
+  )
+  as.character(out)
+}
+attr(formatter_glue_safe, "generator") <- quote(formatter_glue_safe())
+
+wrap_glue <- function(code, inputs, glue_fun, logger_fun) {
+  if (has_rlang()) {
+    withCallingHandlers(
+      code,
+      error = function(cnd) {
+        rlang::abort(
+          c(
+            glue::glue("`{glue_fun}()` failed."),
+            i = glue_hint(conditionMessage(cnd))
+          ),
+          parent = cnd,
+          call = rlang::call2(logger_fun)
+        )
+      }
+    )
+  } else {
+    withCallingHandlers(
+      code,
+      error = function(cnd) {
+        hint <- glue_hint(conditionMessage(cnd))
+        if (!is.null(hint)) hint <- paste0("\n\n", hint)
+
+        stop(paste0(
+          "`", glue_fun, "()` failed in `", logger_fun, "()` on:\n\n",
+          paste0(capture.output(str(inputs)), collapse = ""),
           "\n\nRaw error message:\n\n",
-          e$message,
-          "\n\nPlease consider using another `log_formatter` or",
-          "`skip_formatter` on strings with curly braces."
-        ))
+          conditionMessage(cnd),
+          hint
+        ), call. = FALSE)
       }
     )
+  }
+}
+
+glue_hint <- function(message) {
+  if (!grepl("}", message, fixed = TRUE)) {
+    return()
+  }
+  paste0(
+    "For strings containing `{` or `}` consider using ",
+    "`skip_formatter()` or another `log_formatter`."
   )
 }
-attr(formatter_glue_safe, "generator") <- quote(formatter_glue_safe())
 
+has_rlang <- function() {
+  requireNamespace("rlang", quietly = TRUE)
+}
 
 #' Apply `glue` and `sprintf`
 #'

tests/testthat/_snaps/formatters.md

@@ -19,16 +19,27 @@
     Code
       log_info("hi{")
     Condition
-      Error in `h()`:
-      ! `glue` failed in `formatter_glue` on:
+      Error in `formatter_glue()`:
+      ! `glue()` failed.
+      i For strings containing `{` or `}` consider using `skip_formatter()` or another `log_formatter`.
+      Caused by error in `glue_data()`:
+      ! Expecting '}'
+
+---
+
+    Code
+      log_info("hi{")
+    Condition
+      Error:
+      ! `glue()` failed in `formatter_glue()` on:
 
-       chr "hi{"
+      List of 1 $ : chr "hi{"
 
       Raw error message:
 
       Expecting '}'
 
-      Please consider using another `log_formatter` or `skip_formatter` on strings with curly braces.
+      For strings containing `{` or `}` consider using `skip_formatter()` or another `log_formatter`.
 
 # glue_safe works
 

tests/testthat/test-formatters.R

@@ -38,6 +38,9 @@ test_that("glue works", {
 test_that("glue gives informative error if message contains curlies", {
   local_test_logger(formatter = formatter_glue)
   expect_snapshot(log_info("hi{"), error = TRUE)
+
+  local_mocked_bindings(has_rlang = function() FALSE)
+  expect_snapshot(log_info("hi{"), error = TRUE)
 })
 
 test_that("glue_safe works", {