Add option to automatically record stack trace in logging (fixes #2)

lib/logging.dart

Index: lib/logging.dart
diff --git a/lib/logging.dart b/lib/logging.dart
index 7654885721b1bf3c86dd7ff054b7f9f560313341..70c776b2f8bc610a03e0464f40e8b872f1c277aa 100644
--- a/lib/logging.dart
+++ b/lib/logging.dart
@@ -16,6 +16,12 @@ import 'dart:collection';
 bool hierarchicalLoggingEnabled = false;
 
 /**
+ * Automatically record stack traces for any message of this level or above.
+ * Because this is expensive, this is off by default.
+ */
+Level recordStackTraceAtLevel = Level.OFF;
+
+/**
  * Level for the root-logger. This will be the level of all loggers if
  * [hierarchicalLoggingEnabled] is false.
  */
@@ -147,11 +153,15 @@ class Logger {
   void log(Level logLevel, message,
       [Object error, StackTrace stackTrace, Zone zone]) {
     if (isLoggable(logLevel)) {
-      // If message is a Function, evaluate it.
       if (message is Function) message = message();
-      // If message is still not a String, call toString().
       if (message is! String) message = message.toString();
-      // Only record the current zone if it was not given.
+      if (stackTrace == null && logLevel >= recordStackTraceAtLevel) {
+        try {
+          throw "log stack trace";

[Jennifer Messerly, 2015/05/07 22:32:19]

include message here? e.g.

    throw "log ${logLevel.name} $message"

that might make it more understandable in some tools?

[Siggi Cherem (dart-lang), 2015/05/08 00:31:03]

Good point. Done.

+        } catch (e, t) {
+          stackTrace = t;
+        }
+      }
       if (zone == null) zone = Zone.current;
 
       var record =