Add a "global activate" command to pub.

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

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library pub.command.global_activate;
+
+import 'dart:async';
+
+import '../command.dart';
+import '../utils.dart';
+import '../version.dart';
+
+/// Handles the `global activate` pub command.
+class GlobalActivateCommand extends PubCommand {
+  String get description => "Make a package globally available.";

[nweiz, 2014/06/26 22:43:25]

"a package's executables"

We're going to have to be very careful to make it clear to users that this
doesn't make packages importable globally, since that's the default mode of
operation of most other package managers. It might be a good idea to mention
this when users run "pub help global" as well.

[Bob Nystrom, 2014/06/27 00:30:23]

Yeah, reworded.

+  String get usage => "pub global activate <package> [version]";
+  bool get requiresEntrypoint => false;
+  bool get takesArguments => true;
+
+  Future onRun() {
+    // Make sure there is a package.
+    if (commandOptions.rest.isEmpty) {
+      usageError("No package to activate given.");
+    }
+
+    // Don't allow extra arguments.
+    if (commandOptions.rest.length > 2) {
+      var unexpected = commandOptions.rest.skip(2).map((arg) => '"$arg"');
+      var arguments = pluralize("argument", unexpected.length);
+      usageError("Unexpected $arguments ${toSentence(unexpected)}.");
+    }
+
+    var package = commandOptions.rest.first;
+
+    // Parse the version constraint, if there is one.
+    var constraint = VersionConstraint.any;
+    if (commandOptions.rest.length == 2) {
+      try {
+        constraint = new VersionConstraint.parse(commandOptions.rest[1]);
+      } on FormatException catch (error) {
+        usageError(error.message);
+      }
+    }
+
+    return globals.activate(package, constraint);
+  }
+}