Adapting observe to use smoke (this is built on top of the previous change that

pkg/observe/lib/src/observable.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.observable;
 
 import 'dart:async';
 import 'dart:collection';
 
+// TODO(sigmund): figure out how to remove this annotation entirely
 // Note: ObservableProperty is in this list only for the unusual use case of
 // dart2js without deploy tool. The deploy tool (see "transformer.dart") will
 // add the @reflectable annotation, which makes it work with Polymer's
 // @published.
-@MirrorsUsed(metaTargets: const [Reflectable, ObservableProperty],
-    override: 'observe.src.observable')
-import 'dart:mirrors';
-
+@unused.MirrorsUsed(
+    metaTargets: const [Reflectable, ObservableProperty],
+    override: 'smoke.mirrors')
+import 'dart:mirrors' as unused;

[Jennifer Messerly, 2014/02/20 21:46:40]

import 'dart:mirrors' show MirrorsUsed?

+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
@@ skipping 11 matching lines @@
  */
 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;
-  InstanceMirror _mirror;
 
   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 mirror = reflect(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.
-    for (var type = mirror.type; type != objectType; type = type.superclass) {
-      for (var field in type.declarations.values) {
-        if (field is! VariableMirror ||
-            field.isFinal ||
-            field.isStatic ||
-            field.isPrivate) continue;
-
-        for (var meta in field.metadata) {
-          if (meta.reflectee is ObservableProperty) {
-            var name = field.simpleName;
-            // 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] = mirror.getField(name).reflectee;
-            break;
-          }
-        }
-      }
+    // TODO(sigmund): should we exclude getters here? users should only use
+    // @observable on fields, but 'smoke' includes getters with fields (might
+    // need to extend smoke for this). See also note below on `smoke.read`.
+    var queryOptions = new smoke.QueryOptions(includeInherited: true,

[Jennifer Messerly, 2014/02/20 21:46:40]

hmmm, yeah, it's pretty important not to find getters. They could execute code
(see comment below). Is it hard to add this to pkg:smoke? 

or can you use if (!decl.isProperty) to filter it inside the for loop?

[Siggi Cherem (dart-lang), 2014/02/21 03:50:27]

yeah, I had a feeling this was going to be necessary.

I included in this CL a change in smoke to be able to distinguish isProperty vs
isField and a way to filter it in the query.

+        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);
     }
 
-    _mirror = mirror;
     _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) {
-      _mirror = 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:
@@ skipping 15 matching lines @@
   // 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 = _mirror.getField(name).reflectee;
+      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));
@@ skipping 36 matching lines @@
 // 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;
 }
-
-// NOTE: this is not exported publically.
-final objectType = reflectClass(Object);