Add utility methods to write the contents of a file as one operation.

sdk/lib/io/file_impl.dart

 // Copyright (c) 2012, 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.
 
 class _FileInputStream extends _BaseDataInputStream implements InputStream {
   _FileInputStream(String name)
       : _data = const [],
         _position = 0,
         _filePosition = 0 {
     var file = new File(name);
@@ skipping 642 matching lines @@
     });
   }
 
   List<String> readAsLinesSync([Encoding encoding = Encoding.UTF_8]) {
     var decoder = _StringDecoders.decoder(encoding);
     List<int> bytes = readAsBytesSync();
     decoder.write(bytes);
     return _getDecodedLines(decoder);
   }
 
+  Future<File> writeAsBytes(List<int> bytes,
+                            [FileMode mode = FileMode.WRITE]) {
+    Completer<File> completer = new Completer<File>();
+    try {
+      var stream = openOutputStream(mode);
+      stream.write(bytes);

[Søren Gjesse, 2012/11/20 13:23:34]

You could just do stream.close() right after stream.write and place a handler on
onClose instead of on onNoPendingWrites.

+      stream.onNoPendingWrites = () {
+        stream.close();
+        stream.onClosed = () {
+          completer.complete(this);
+        };
+      };
+      stream.onError = (e) {
+        completer.completeException(e);
+      };
+    } catch (e) {
+      new Timer(0, (t) => completer.completeException(e));
+      return completer.future;
+    }
+    return completer.future;
+  }
+
+  void writeAsBytesSync(List<int> bytes, [FileMode mode = FileMode.WRITE]) {
+    RandomAccessFile opened = openSync(mode);
+    opened.writeListSync(bytes, 0, bytes.length);
+    opened.closeSync();
+  }
+
+  Future<File> writeAsString(String contents,
+                             [FileMode mode = FileMode.WRITE,
+                              Encoding encoding = Encoding.UTF_8]) {
+    try {
+      var data = _StringEncoders.encoder(encoding).encodeString(contents);
+      return writeAsBytes(data, mode);
+    } catch (e) {
+      var completer = new Completer();
+      new Timer(0, (t) => completer.completeException(e));
+      return completer.future;
+    }
+  }
+
+  void writeAsStringSync(String contents,
+                         [FileMode mode = FileMode.WRITE,
+                          Encoding encoding = Encoding.UTF_8]) {
+    var data = _StringEncoders.encoder(encoding).encodeString(contents);
+    writeAsBytesSync(data, mode);
+  }
+
   String get name => _name;
 
   void _ensureFileService() {
     if (_fileService == null) {
       _fileService = _FileUtils._newServicePort();
     }
   }
 
   static throwIfError(Object result, String msg) {
     if (result is OSError) {
@@ skipping 407 matching lines @@
           new FileIOException("File closed '$_name'"));
     });
     return completer.future;
   }
 
   final String _name;
   int _id;
 
   SendPort _fileService;
 }