"Reverting 22561"

pkg/mdv_observe/lib/src/observable_box.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.
-
-part of mdv_observe;
-
-// TODO(jmesserly): should the property name be configurable?
-// That would be more convenient.
-/**
- * An observable box that holds a value. Use this if you want to store a single
- * value. For other cases, it is better to use [ObservableList],
- * [ObservableMap], or a custom [Observable] implementation based on
- * [ObservableMixin]. The property name for changes is "value".
- */
-class ObservableBox<T> extends ObservableBase {
-  static const _VALUE = const Symbol('value');
-
-  T _value;
-
-  ObservableBox([T initialValue]) : _value = initialValue;
-
-  T get value => _value;
-
-  void set value(T newValue) {
-    _value = notifyPropertyChange(_VALUE, _value, newValue);
-  }
-
-  String toString() => '#<$runtimeType value: $value>';
-
-  getValueWorkaround(key) {
-    if (key == _VALUE) return value;
-    return null;
-  }
-  void setValueWorkaround(key, newValue) {
-    if (key == _VALUE) value = newValue;
-  }
-}