Exit with an error on unexpected command line arguments.

sdk/lib/_internal/pub/lib/src/command.dart

Index: sdk/lib/_internal/pub/lib/src/command.dart
diff --git a/sdk/lib/_internal/pub/lib/src/command.dart b/sdk/lib/_internal/pub/lib/src/command.dart
index fe899cdbae66a62604e1bd516d4f4c52786c2c63..e8b7ed0e09fa14a9589802d0ed8de194b61dd5bc 100644
--- a/sdk/lib/_internal/pub/lib/src/command.dart
+++ b/sdk/lib/_internal/pub/lib/src/command.dart
@@ -31,7 +31,7 @@ import 'utils.dart';
 
 /// The base class for commands for the pub executable.
 abstract class PubCommand {
-  /// The commands that Pub understands.
+  /// The commands that pub understands.
   static final Map<String, PubCommand> commands = _initCommands();
 
   SystemCache cache;
@@ -52,9 +52,13 @@ abstract class PubCommand {
   String get usage;
 
   /// Whether or not this command requires [entrypoint] to be defined. If false,
-  /// Pub won't look for a pubspec and [entrypoint] will be null when the
+  /// pub won't look for a pubspec and [entrypoint] will be null when the
   /// command runs.
-  final requiresEntrypoint = true;
+  bool get requiresEntrypoint => true;

[nweiz, 2013/10/16 21:46:32]

Why is this a getter now?

[Bob Nystrom, 2013/10/29 01:02:12]

Kind of pedantic here, but there's no point in adding state to each instance for
this when all instances will have the same value. A getter makes it explicit
that it's a property of the class.

[nweiz, 2013/10/29 19:21:33]

I don't think this communicates what you're trying to communicate. The Dart
language takes pains to make fields and getters interchangeable, so when I see a
(more verbose) getter somewhere where a field would do, I don't read that as
saying "all instances will have the same value", since that would be true for a
final field as well. I just read it as confusing.

If there's a significant memory benefit to be had by not allocating space for
the constant field, I'm sure the VM is smart enough to do that on its own.

[Bob Nystrom, 2013/10/29 19:43:42]

For me, this isn't an optimization issue. I don't like state in general because
it makes code harder to reason about. I try to minimize the amount of state a
program has. In this case, each instance doesn't need a field so I'd rather use
a getter.

[nweiz, 2013/10/29 21:03:08]

A final field with a constant value isn't state. It can't change in any way
ever, and that's clear from looking at the declaration. It's identical to a
getter, both in terms of language semantics and what the declarations
communicate. The only difference is that a getter is more verbose and thus
confusing to a reader looking for a reason for that verbosity.

+
+  /// Whether or not this command takes arguments in addition to options. If
+  /// false, pub will exit with an error if arguments are provided.
+  bool get takesArguments => false;
 
   /// Alternate names for this command. These names won't be used in the
   /// documentation, but they will work when invoked on the command line.
@@ -117,6 +121,13 @@ and include the results in a bug report on http://dartbug.com/new.
     }
 
     new Future.sync(() {
+      // Make sure there aren't unexpected arguments.
+      if (!takesArguments && commandOptions.rest.isNotEmpty) {
+        log.error('Command does not take any arguments.');

[nweiz, 2013/10/16 21:46:32]

Include the command name.

[Bob Nystrom, 2013/10/29 01:02:12]

Done.

+        this.printUsage();
+        return flushThenExit(exit_codes.USAGE);
+      }
+
       if (requiresEntrypoint) {
         // TODO(rnystrom): Will eventually need better logic to walk up
         // subdirectories until we hit one that looks package-like. For now,