Merge pull request #710 from abarth/const_key

Key should be const

examples/widgets/tabs.dart

@@ -35,7 +35,7 @@ class TabbedNavigatorApp extends App {
           builder: () => _buildContent(text)
         );
       });
-    return _buildTabNavigator(n, views.toList(), new Key('textLabelsTabNavigator'));
+    return _buildTabNavigator(n, views.toList(), const StringKey('textLabelsTabNavigator'));
   }
 
   TabNavigator _buildIconLabelsTabNavigator(int n) {
@@ -46,7 +46,7 @@ class TabbedNavigatorApp extends App {
           builder: () => _buildContent(icon_name)
         );
       });
-    return _buildTabNavigator(n, views.toList(), new Key('iconLabelsTabNavigator'));
+    return _buildTabNavigator(n, views.toList(), const StringKey('iconLabelsTabNavigator'));
   }
 
   TabNavigator _buildTextAndIconLabelsTabNavigator(int n) {
@@ -64,7 +64,7 @@ class TabbedNavigatorApp extends App {
         builder: () => _buildContent("Summary")
       )
     ];
-    return _buildTabNavigator(n, views, new Key('textAndIconLabelsTabNavigator'));
+    return _buildTabNavigator(n, views, const StringKey('textAndIconLabelsTabNavigator'));
   }
 
   TabNavigator _buildScrollableTabNavigator(int n) {
@@ -86,7 +86,7 @@ class TabbedNavigatorApp extends App {
           builder: () => _buildContent(text)
         );
       });
-    return _buildTabNavigator(n, views.toList(), new Key('scrollableTabNavigator'), isScrollable: true);
+    return _buildTabNavigator(n, views.toList(), const StringKey('scrollableTabNavigator'), isScrollable: true);
   }
 
 
@@ -118,7 +118,7 @@ class TabbedNavigatorApp extends App {
       )
     ];
 
-    TabNavigator tabNavigator = _buildTabNavigator(4, views, new Key('tabs'));
+    TabNavigator tabNavigator = _buildTabNavigator(4, views, const StringKey('tabs'));
     assert(selectedIndices.length == 5);
 
     ToolBar toolbar = new ToolBar(

packages/flutter/lib/editing/input.dart

@@ -8,6 +8,7 @@ import 'package:sky/mojo/keyboard.dart';
 import 'package:sky/painting/text_style.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/focus.dart';
+import 'package:sky/widgets/framework.dart';
 import 'package:sky/widgets/theme.dart';
 
 export 'package:sky/mojo/keyboard.dart' show KeyboardType_TEXT, KeyboardType_NUMBER, KeyboardType_PHONE, KeyboardType_DATETIME;
@@ -74,7 +75,7 @@ class Input extends StatefulComponent {
 
     if (placeholder != null && _value.isEmpty) {
       Widget child = new Opacity(
-        key: new Key('placeholder'),
+        key: const StringKey('placeholder'),
         child: new Text(placeholder, style: textStyle),
         opacity: themeData.hintOpacity
       );

packages/flutter/lib/widgets/framework.dart

@@ -25,14 +25,14 @@ typedef Widget Builder();
 typedef void WidgetTreeWalker(Widget);
 
 abstract class Key {
-  Key.constructor(); // so that subclasses can call us, since the Key() factory constructor shadows the implicit constructor
+  const Key.constructor(); // so that subclasses can call us, since the Key() factory constructor shadows the implicit constructor
   factory Key(String value) => new StringKey(value);
   factory Key.stringify(Object value) => new StringKey(value.toString());
   factory Key.fromObjectIdentity(Object value) => new ObjectKey(value);
 }
 
 class StringKey extends Key {
-  StringKey(this.value) : super.constructor();
+  const StringKey(this.value) : super.constructor();
   final String value;
   String toString() => '[\'${value}\']';
   bool operator==(other) => other is StringKey && other.value == value;
@@ -40,7 +40,7 @@ class StringKey extends Key {
 }
 
 class ObjectKey extends Key {
-  ObjectKey(this.value) : super.constructor();
+  const ObjectKey(this.value) : super.constructor();
   final Object value;
   String toString() => '[${value.runtimeType}(${value.hashCode})]';
   bool operator==(other) => other is ObjectKey && identical(other.value, value);
@@ -50,7 +50,7 @@ class ObjectKey extends Key {
 typedef void GlobalKeyRemovalListener(GlobalKey key);
 
 abstract class GlobalKey extends Key {
-  GlobalKey.constructor() : super.constructor(); // so that subclasses can call us, since the Key() factory constructor shadows the implicit constructor
+  const GlobalKey.constructor() : super.constructor(); // so that subclasses can call us, since the Key() factory constructor shadows the implicit constructor
   factory GlobalKey({ String label }) => new LabeledGlobalKey(label);
   factory GlobalKey.fromObjectIdentity(Object value) => new GlobalObjectKey(value);
 
@@ -136,13 +136,13 @@ abstract class GlobalKey extends Key {
 
 class LabeledGlobalKey extends GlobalKey {
   // the label is purely for documentary purposes and does not affect the key
-  LabeledGlobalKey(this._label) : super.constructor();
+  const LabeledGlobalKey(this._label) : super.constructor();
   final String _label;
   String toString() => '[GlobalKey ${_label != null ? _label : hashCode}]';
 }
 
 class GlobalObjectKey extends GlobalKey {
-  GlobalObjectKey(this.value) : super.constructor();
+  const GlobalObjectKey(this.value) : super.constructor();
   final Object value;
   String toString() => '[GlobalKey ${value.runtimeType}(${value.hashCode})]';
   bool operator==(other) => other is GlobalObjectKey && identical(other.value, value);