Add a generate script to generate the googleapis libraries.

bin/generate.dart

+#!/usr/bin/env dart
+
+// Copyright (c) 2015, 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.
+
+import "dart:io";
+
+import "package:args/args.dart";
+import "package:googleapis_generator_dependency/googleapis_generator.dart";
+
+ArgParser downloadCommandArgParser() {
+  return new ArgParser()
+      ..addOption('output-dir',
+                  abbr: 'o',
+                  help: 'Output directory of discovery documents.',
+                  defaultsTo: 'googleapis-discovery-documents');
+}
+
+ArgParser runConfigCommandArgParser() {
+  return new ArgParser()
+      ..addOption('config-file',
+                  help: 'Configuration file describing package generation.',
+                  defaultsTo: 'config.yaml');
+}
+
+ArgParser globalArgParser() {
+  return new ArgParser()
+      ..addCommand('download', downloadCommandArgParser())
+      ..addCommand('run_config', runConfigCommandArgParser())
+      ..addFlag('help', abbr: 'h', help: 'Displays usage information.');
+}
+
+ArgResults parseArguments(ArgParser parser, List<String> arguments) {
+  try {
+    return parser.parse(arguments);
+  } on FormatException catch(e) {
+    dieWithUsage("Error parsing arguments:\n${e.message}\n");
+  }
+}
+
+void dieWithUsage([String message]) {
+  if (message != null) {
+    print(message);
+  }
+  print("Usage:");
+  print("The discovery generator has the following sub-commands:");
+  print("");
+  print("  download");
+  print("  run_config");
+  print("");
+  print("The 'download' subcommand downloads all discovery documents. "
+        "It takes the following options:");
+  print("");
+  print(downloadCommandArgParser().usage);
+  print("");
+  print("The 'run_config' subcommand downloads discovery documents and "
+        "generates one or more API packages based on a configuration file. "
+        "It takes the following options:");
+  print("");
+  print(runConfigCommandArgParser().usage);
+  exit(1);
+}
+
+void main(List<String> arguments) {
+  var parser = globalArgParser();
+  var options = parseArguments(parser, arguments);
+  var commandOptions = options.command;
+  var subCommands = ['download', 'generate', 'run_config'];

[kustermann, 2015/03/12 15:46:42]

Remove 'generate' here?

+
+  if (options['help']) {
+    dieWithUsage();
+  } else if (commandOptions == null ||
+             !subCommands.contains(commandOptions.name)) {
+    dieWithUsage('Invalid command');
+  }
+
+  switch (commandOptions.name) {
+    case 'download':
+      downloadDiscoveryDocuments(commandOptions['output-dir']);
+      break;
+    case 'run_config':
+      var configFile = commandOptions['config-file'];
+      generateFromConfiguration(configFile).then((_) => print('Done!'));
+      break;
+  }
+}