More comments to StringBuffers.

sdk/lib/core/string_buffer.dart

 // Copyright (c) 2011, 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.
 
 part of dart.core;
 
 /**
  * The StringBuffer class is useful for concatenating strings
  * efficiently. Only on a call to [toString] are the strings
  * concatenated to a single String.
  */
 class StringBuffer implements StringSink {
 
-  /// Creates the string buffer with an initial content.
+  /** Creates the string buffer with an initial content. */
   external StringBuffer([Object content = ""]);
 
-  /// Returns the length of the buffer.
+  /**
+   * Returns the length of the content that has been accumulated so far.
+   * This is a constant-time operation.
+   */
   external int get length;
 
-  /// Returns whether the buffer is empty.
+  /** Returns whether the buffer is empty. This is a constant-time operation. */
   bool get isEmpty => length == 0;
 
   /**
    * Converts [obj] to a string and adds it to the buffer.
    *
    * *Deprecated*. Use [write] instead.
    */
   @deprecated
   void add(Object obj) => write(obj);
 
@@ skipping 37 matching lines @@
    * Clears the string buffer.
    *
    * *Deprecated*.
    */
   @deprecated
   external void clear();
 
   /// Returns the contents of buffer as a concatenated string.
   external String toString();
 }