Handle errors in display functions more gracefully and isolate full html pages

R/execution.r

@@ -148,7 +148,7 @@ execute = function(request) {
 
     err <<- list()
     nframe <- NULL  # find out stack depth in notebook cell
-    
+
     tryCatch(evaluate(
         'stop()',
         stop_on_error = 1L,
@@ -174,25 +174,57 @@ execute = function(request) {
         handle_message  <- identity
         handle_warning  <- identity
     } else {
+        handle_display_error <- function(e){
+            # This is used with withCallingHandler and only has two additional
+            # calls at the end instead of the 3 for tryCatch... (-2 at the end)
+            # we also remove the tryCatch and mime2repr stuff at the head of the callstack (+7)
+            calls <- head(sys.calls()[-seq_len(nframe + 7L)], -2)
+            stack_info <- format_stack(calls)
+            msg <- sprintf('ERROR while rich displaying an object: %s\nTraceback:\n%s\n',
+                           toString(e),
+                           paste(stack_info, collapse='\n'))
+            log_debug(msg)
+            if (!silent) {
+                send_response('stream', request, 'iopub', list(
+                    name = 'stderr',
+                    text = msg))
+            }
+        }
         handle_value <- function(obj) {
             data <- namedlist()
+            metadata <- namedlist()
+
             data[['text/plain']] <- repr_text(obj)
 
             # Only send a response when there is regular console output
             if (nchar(data[['text/plain']]) > 0) {
                 if (getOption('jupyter.rich_display')) {
-                    tryCatch({
-                        for (mime in getOption('jupyter.display_mimetypes')) {
+                    for (mime in getOption('jupyter.display_mimetypes')) {
+                        # Use withCallingHandlers as that shows the inner stacktrace:
+                        # https://stackoverflow.com/questions/15282471/get-stack-trace-on-trycatched-error-in-r
+                        # the tryCatch is  still needed to prevent the error from showing
+                        # up outside further up the stack :-/
+                        tryCatch(withCallingHandlers({
                             r <- mime2repr[[mime]](obj)
-                            if (!is.null(r)) data[[mime]] <- r
-                        }
-                    }, error = handle_error)
+                            if (!is.null(r)) {
+                                data[[mime]] <- r
+                                # Isolating full html pages (putting them in an iframe)
+                                if (identical(mime, 'text/html')) {
+                                    if (grepl("<html.*>", r, ignore.case = TRUE)){
+                                        jupyter_debug("Found full html page: %s", strtrim(r, 100))
+                                        metadata[[mime]] <- list(isolated = TRUE)
+                                    }
+                                }
+                            }
+                        }, error = handle_display_error),
+                        error = function(x) {})
+                    }
                 }
-
-                send_response('display_data', request, 'iopub', list(
-                    data = data,
-                    metadata = namedlist() ))
             }
+            log_debug("Sending display_data: %s", paste(capture.output(str(data)), collapse = "\n"))
+            send_response('display_data', request, 'iopub', list(
+                data = data,
+                metadata = metadata))
         }
 
         stream <- function(output, streamname) {

test_ir.py

@@ -26,6 +26,16 @@ class InstallspecTests(jkt.KernelTests):
 
     code_hello_world = 'print("hello, world")'
 
+class DisplaySystem(jkt.KernelTests):
+    kernel_name = 'ir'
+
+    language_name = 'R'
+
+    code_display_data = [
+    {'code': 'options(jupyter.rich_display = FALSE);cat("a")', 'mime': {'text/plain':'a'}},
+    {'code': '"a"', 'mime': {'text/plain':'"a"'}},
+    {'code': '1:3', 'mime': {'text/plain':'[1] 1 2 3'}},
+    ]
 
 if __name__ == '__main__':
     unittest.main()