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Unified Diff: pkg/observe/lib/src/observable.dart

Issue 817483003: delete observe from the repo (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart
Patch Set: Created 6 years ago
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Index: pkg/observe/lib/src/observable.dart
diff --git a/pkg/observe/lib/src/observable.dart b/pkg/observe/lib/src/observable.dart
deleted file mode 100644
index eee62f2cebdb5e482fb2b75f95996fc113b1d7c9..0000000000000000000000000000000000000000
--- a/pkg/observe/lib/src/observable.dart
+++ /dev/null
@@ -1,169 +0,0 @@
-// 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.observable;
-
-import 'dart:async';
-import 'dart:collection';
-
-import 'package:smoke/smoke.dart' as smoke;
-import 'package:observe/observe.dart';
-
-// Note: this is an internal library so we can import it from tests.
-// TODO(jmesserly): ideally we could import this with a prefix, but it caused
-// strange problems on the VM when I tested out the dirty-checking example
-// above.
-import 'dirty_check.dart';
-
-/// Represents an object with observable properties. This is used by data in
-/// model-view architectures to notify interested parties of [changes] to the
-/// object's properties (fields or getter/setter pairs).
-///
-/// The interface does not require any specific technique to implement
-/// observability. You can implement it in the following ways:
-///
-/// - extend or mixin this class, and let the application call [dirtyCheck]
-/// periodically to check for changes to your object.
-/// - extend or mixin [ChangeNotifier], and implement change notifications
-/// manually by calling [notifyPropertyChange] from your setters.
-/// - implement this interface and provide your own implementation.
-abstract class Observable {
- /// Performs dirty checking of objects that inherit from [Observable].
- /// This scans all observed objects using mirrors and determines if any fields
- /// have changed. If they have, it delivers the changes for the object.
- static void dirtyCheck() => dirtyCheckObservables();
-
- StreamController _changes;
-
- Map<Symbol, Object> _values;
- List<ChangeRecord> _records;
-
- /// The stream of change records to this object. Records will be delivered
- /// asynchronously.
- ///
- /// [deliverChanges] can be called to force synchronous delivery.
- Stream<List<ChangeRecord>> get changes {
- if (_changes == null) {
- _changes = new StreamController.broadcast(sync: true,
- onListen: _observed, onCancel: _unobserved);
- }
- return _changes.stream;
- }
-
- /// True if this object has any observers, and should call
- /// [notifyChange] for changes.
- bool get hasObservers => _changes != null && _changes.hasListener;
-
- void _observed() {
- // Register this object for dirty checking purposes.
- registerObservable(this);
-
- var values = new Map<Symbol, Object>();
-
- // Note: we scan for @observable regardless of whether the base type
- // actually includes this mixin. While perhaps too inclusive, it lets us
- // avoid complex logic that walks "with" and "implements" clauses.
- var queryOptions = new smoke.QueryOptions(includeInherited: true,
- includeProperties: false, withAnnotations: const [ObservableProperty]);
- for (var decl in smoke.query(this.runtimeType, queryOptions)) {
- var name = decl.name;
- // Note: since this is a field, getting the value shouldn't execute
- // user code, so we don't need to worry about errors.
- values[name] = smoke.read(this, name);
- }
-
- _values = values;
- }
-
- /// Release data associated with observation.
- void _unobserved() {
- // Note: we don't need to explicitly unregister from the dirty check list.
- // This will happen automatically at the next call to dirtyCheck.
- if (_values != null) {
- _values = null;
- }
- }
-
- /// Synchronously deliver pending [changes]. Returns true if any records were
- /// delivered, otherwise false.
- // TODO(jmesserly): this is a bit different from the ES Harmony version, which
- // allows delivery of changes to a particular observer:
- // http://wiki.ecmascript.org/doku.php?id=harmony:observe#object.deliverchangerecords
- //
- // The rationale for that, and for async delivery in general, is the principal
- // that you shouldn't run code (observers) when it doesn't expect to be run.
- // If you do that, you risk violating invariants that the code assumes.
- //
- // For this reason, we need to match the ES Harmony version. The way we can do
- // this in Dart is to add a method on StreamSubscription (possibly by
- // subclassing Stream* types) that immediately delivers records for only
- // that subscription. Alternatively, we could consider using something other
- // than Stream to deliver the multicast change records, and provide an
- // Observable->Stream adapter.
- //
- // Also: we should be delivering changes to the observer (subscription) based
- // on the birth order of the observer. This is for compatibility with ES
- // Harmony as well as predictability for app developers.
- bool deliverChanges() {
- if (_values == null || !hasObservers) return false;
-
- // Start with manually notified records (computed properties, etc),
- // then scan all fields for additional changes.
- List records = _records;
- _records = null;
-
- _values.forEach((name, oldValue) {
- var newValue = smoke.read(this, name);
- if (oldValue != newValue) {
- if (records == null) records = [];
- records.add(new PropertyChangeRecord(this, name, oldValue, newValue));
- _values[name] = newValue;
- }
- });
-
- if (records == null) return false;
-
- _changes.add(new UnmodifiableListView<ChangeRecord>(records));
- return true;
- }
-
- /// Notify that the field [name] of this object has been changed.
- ///
- /// The [oldValue] and [newValue] are also recorded. If the two values are
- /// equal, no change will be recorded.
- ///
- /// For convenience this returns [newValue].
- notifyPropertyChange(Symbol field, Object oldValue, Object newValue)
- => notifyPropertyChangeHelper(this, field, oldValue, newValue);
-
- /// Notify observers of a change.
- ///
- /// For most objects [Observable.notifyPropertyChange] is more convenient, but
- /// collections sometimes deliver other types of changes such as a
- /// [ListChangeRecord].
- ///
- /// Notes:
- /// - This is *not* required for fields if you mixin or extend [Observable],
- /// but you can use it for computed properties.
- /// - Unlike [ChangeNotifier] this will not schedule [deliverChanges]; use
- /// [Observable.dirtyCheck] instead.
- void notifyChange(ChangeRecord record) {
- if (!hasObservers) return;
-
- if (_records == null) _records = [];
- _records.add(record);
- }
-}
-
-// TODO(jmesserly): remove the instance method and make this top-level method
-// public instead?
-// NOTE: this is not exported publically.
-notifyPropertyChangeHelper(Observable obj, Symbol field, Object oldValue,
- Object newValue) {
-
- if (obj.hasObservers && oldValue != newValue) {
- obj.notifyChange(new PropertyChangeRecord(obj, field, oldValue, newValue));
- }
- return newValue;
-}
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