pkg/observe/lib/src/change_record.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.

library observe.src.change_record;

import 'package:observe/observe.dart';


/** Records a change to an [Observable]. */
// TODO(jmesserly): remove this type
abstract class ChangeRecord {}

/** A change record to a field of an observable object. */
class PropertyChangeRecord<T> extends ChangeRecord {
  /** The object that changed. */
  final object;

  /** The name of the property that changed. */
  final Symbol name;

  /** The previous value of the property. */
  final T oldValue;

  /** The new value of the property. */
  final T newValue;

  PropertyChangeRecord(this.object, this.name, this.oldValue, this.newValue);

  String toString() =>
      '#<PropertyChangeRecord $name from: $oldValue to: $newValue>';
}