Add a --trace flag to make Pub print a stack trace on error.

utils/pub/pub.dart

Index: utils/pub/pub.dart
diff --git a/utils/pub/pub.dart b/utils/pub/pub.dart
index adbe5ea616dab07cab3c89676bf52f93176f548b..c01657d2df706c1620d90ee76cf6c37d318202bd 100644
--- a/utils/pub/pub.dart
+++ b/utils/pub/pub.dart
@@ -48,6 +48,7 @@ main() {
   parser.addOption('cachedir', help: 'The directory containing the system-wide '
     'Pub cache');
   parser.addOption('sdkdir', help: 'The directory containing the Dart SDK');
+  parser.addFlag('trace', help: 'Prints a stack trace when an error occurs');
 
   var results;
   try {
@@ -83,7 +84,8 @@ main() {
     return;
   }
 
-  command.run(cache, results.rest.getRange(1, results.rest.length - 1));
+  var args = results.rest.getRange(1, results.rest.length - 1);
+  command.run(cache, results, args);

[Bob Nystrom, 2012/07/09 23:00:36]

These names aren't very clear. How about:

results -> globalOptions
args -> commandArgs

[nweiz, 2012/07/09 23:38:09]

Done.

 }
 
 /** Displays usage information for the app. */
@@ -128,13 +130,13 @@ class PubCommand {
 
   abstract String get description();
 
-  void run(SystemCache cache_, List<String> args) {
+  void run(SystemCache cache_, ArgResults options, List<String> args) {
     cache = cache_;
 
     // TODO(rnystrom): Each command should define the arguments it expects and
     // we can handle them generically here.
 
-    handleError(error) {
+    handleError(error, trace) {
       // This is basically the top-level exception handler so that we don't
       // spew a stack trace on our users.
       // TODO(rnystrom): Add --trace flag so stack traces can be enabled for
@@ -148,13 +150,16 @@ class PubCommand {
       }
 
       printError(message);
+      if (options['trace'] && trace != null) {
+        printError(trace);
+      }
       return true;
     }
 
     // TODO(rnystrom): Will eventually need better logic to walk up
     // subdirectories until we hit one that looks package-like. For now, just
     // assume the cwd is it.
-    Package.load(workingDir, cache.sources).chain((package) {
+    var future = Package.load(workingDir, cache.sources).chain((package) {
       entrypoint = new Entrypoint(package, cache);
 
       try {
@@ -162,11 +167,12 @@ class PubCommand {
         if (commandFuture == null) return new Future.immediate(true);
 
         return commandFuture;
-      } catch (var error) {
-        handleError(error);
+      } catch (var error, var trace) {
+        handleError(error, trace);
         return new Future.immediate(null);
       }
-    }).handleException(handleError);
+    });
+    future.handleException((e) => handleError(e, future.stackTrace));
   }
 
   /**