Formatter main overwrite flag fix.

pkg/analyzer_experimental/bin/formatter.dart

 #!/usr/bin/env dart
 
 // Copyright (c) 2013, 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:path/path.dart' as path;
 
 import 'package:analyzer_experimental/src/services/formatter_impl.dart';
 
 
 const BINARY_NAME = 'dartfmt';
 final dartFileRegExp = new RegExp(r'^[^.].*\.dart$', caseSensitive: false);
 final argParser = _initArgParser();
 
+bool overwriteFileContents;
+
 void main() {
   var options = argParser.parse(new Options().arguments);
   if (options['help']) {
     _printUsage();
     return;
   }
+  overwriteFileContents = options['write'];
+  
   if (options.rest.isEmpty) {
     _formatStdin(options);
   } else {
     _formatPaths(options.rest);
   }
 }
 
 _formatPaths(paths) {
   paths.forEach((path) {
     if (FileSystemEntity.isDirectorySync(path)) {
       _formatDirectory(new Directory(path));
     } else {
       _formatFile(new File(path));
     }
   });
 }
 
 _formatResource(resource) {
   if (resource is Directory) {
     _formatDirectory(resource);
   } else if (resource is File) {
     _formatFile(resource);
   }
 }
 
 _formatDirectory(dir) => 
     dir.listSync().forEach((resource) => _formatResource(resource));
 
-
 void _formatFile(file) {
   if (_isDartFile(file)) {
     try {
       var buffer = new StringBuffer();
       var rawSource = file.readAsStringSync();
       var formatted = _formatCU(rawSource);
-      print(formatted);
-      file.writeAsStringSync(formatted);
+      if (overwriteFileContents) {
+        file.writeAsStringSync(formatted);
+      } else {
+        print(formatted);
+      }
     } catch (e) {
       _log('Error formatting "${file.path}": $e');
     }
   }
 }
 
 _isDartFile(file) => dartFileRegExp.hasMatch(path.basename(file.path));
 
 _formatStdin(options) {
   _log('not supported yet!');
@@ skipping 36 matching lines @@
 
 /// Format the given [src] as a compilation unit.
 String _formatCU(src, {options: const FormatterOptions()}) =>
     new CodeFormatter(options).format(CodeKind.COMPILATION_UNIT, src);
 
 /// Log the given [msg].
 _log(String msg) {
   //TODO(pquitslund): add proper log support
   print(msg);
 }