Refactor the Stocks app's settings

This will make it much easier to add more settings.

examples/stocks/lib/main.dart

@@ -37,6 +37,12 @@ class StocksAppState extends State<StocksApp> {
   final Map<String, Stock> _stocks = <String, Stock>{};
   final List<String> _symbols = <String>[];
 
+  StockConfiguration _configuration = new StockConfiguration(
+    stockMode: StockMode.optimistic,
+    backupMode: BackupMode.enabled,
+    showGrid: false
+  );
+
   void initState() {
     super.initState();
     new StockDataFetcher((StockData data) {
@@ -46,27 +52,14 @@ class StocksAppState extends State<StocksApp> {
     });
   }
 
-  StockMode _optimismSetting = StockMode.optimistic;
-  BackupMode _backupSetting = BackupMode.disabled;
-  bool _showGridSetting = false;
-  void modeUpdater(StockMode optimism) {
+  void configurationUpdater(StockConfiguration value) {
     setState(() {
-      _optimismSetting = optimism;
-    });
-  }
-  void settingsUpdater({ StockMode optimism, BackupMode backup, bool showGrid }) {
-    setState(() {
-      if (optimism != null)
-        _optimismSetting = optimism;
-      if (backup != null)
-        _backupSetting = backup;
-      if (showGrid != null)
-        _showGridSetting = showGrid;
+      _configuration = value;
     });
   }
 
   ThemeData get theme {
-    switch (_optimismSetting) {
+    switch (_configuration.stockMode) {
       case StockMode.optimistic:
         return new ThemeData(
           brightness: ThemeBrightness.light,
@@ -108,10 +101,10 @@ class StocksAppState extends State<StocksApp> {
     return new MaterialApp(
       title: 'Stocks',
       theme: theme,
-      debugShowMaterialGrid: _showGridSetting,
+      debugShowMaterialGrid: _configuration.showGrid,
       routes: <String, RouteBuilder>{
-         '/':         (RouteArguments args) => new StockHome(_stocks, _symbols, _optimismSetting, modeUpdater),
-         '/settings': (RouteArguments args) => new StockSettings(_optimismSetting, _backupSetting, _showGridSetting, settingsUpdater)
+         '/':         (RouteArguments args) => new StockHome(_stocks, _symbols, _configuration, configurationUpdater),
+         '/settings': (RouteArguments args) => new StockSettings(_configuration, configurationUpdater)
       },
       onGenerateRoute: _getRoute,
       onLocaleChanged: _onLocaleChanged

examples/stocks/lib/stock_home.dart

@@ -9,12 +9,12 @@ typedef void ModeUpdater(StockMode mode);
 enum StockHomeTab { market, portfolio }
 
 class StockHome extends StatefulComponent {
-  StockHome(this.stocks, this.symbols, this.stockMode, this.modeUpdater);
+  const StockHome(this.stocks, this.symbols, this.configuration, this.updater);
 
   final Map<String, Stock> stocks;
   final List<String> symbols;
-  final StockMode stockMode;
-  final ModeUpdater modeUpdater;
+  final StockConfiguration configuration;
+  final ValueChanged<StockConfiguration> updater;
 
   StockHomeState createState() => new StockHomeState();
 }
@@ -25,10 +25,6 @@ class StockHomeState extends State<StockHome> {
   bool _isSearching = false;
   String _searchQuery;
 
-  void initState() {
-    super.initState();
-  }
-
   void _handleSearchBegin() {
     ModalRoute.of(context).addLocalHistoryEntry(new LocalHistoryEntry(
       onRemove: () {
@@ -61,8 +57,8 @@ class StockHomeState extends State<StockHome> {
   }
 
   void _handleStockModeChange(StockMode value) {
-    if (config.modeUpdater != null)
-      config.modeUpdater(value);
+    if (config.updater != null)
+      config.updater(config.configuration.copyWith(stockMode: value));
   }
 
   void _handleMenuShow() {
@@ -120,7 +116,7 @@ class StockHomeState extends State<StockHome> {
           onPressed: () => _handleStockModeChange(StockMode.optimistic),
           child: new Row(<Widget>[
             new Flexible(child: new Text('Optimistic')),
-            new Radio<StockMode>(value: StockMode.optimistic, groupValue: config.stockMode, onChanged: _handleStockModeChange)
+            new Radio<StockMode>(value: StockMode.optimistic, groupValue: config.configuration.stockMode, onChanged: _handleStockModeChange)
           ])
         ),
         new DrawerItem(
@@ -128,7 +124,7 @@ class StockHomeState extends State<StockHome> {
           onPressed: () => _handleStockModeChange(StockMode.pessimistic),
           child: new Row(<Widget>[
             new Flexible(child: new Text('Pessimistic')),
-            new Radio<StockMode>(value: StockMode.pessimistic, groupValue: config.stockMode, onChanged: _handleStockModeChange)
+            new Radio<StockMode>(value: StockMode.pessimistic, groupValue: config.configuration.stockMode, onChanged: _handleStockModeChange)
           ])
         ),
         new DrawerDivider(),

examples/stocks/lib/stock_settings.dart

@@ -4,19 +4,11 @@
 
 part of stocks;
 
-typedef void SettingsUpdater({
-  StockMode optimism,
-  BackupMode backup,
-  bool showGrid
-});
-
 class StockSettings extends StatefulComponent {
-  const StockSettings(this.optimism, this.backup, this.showGrid, this.updater);
+  const StockSettings(this.configuration, this.updater);
 
-  final StockMode optimism;
-  final BackupMode backup;
-  final SettingsUpdater updater;
-  final bool showGrid;
+  final StockConfiguration configuration;
+  final ValueChanged<StockConfiguration> updater;
 
   StockSettingsState createState() => new StockSettingsState();
 }
@@ -24,19 +16,19 @@ class StockSettings extends StatefulComponent {
 class StockSettingsState extends State<StockSettings> {
   void _handleOptimismChanged(bool value) {
     value ??= false;
-    sendUpdates(value ? StockMode.optimistic : StockMode.pessimistic, config.backup, config.showGrid);
+    sendUpdates(config.configuration.copyWith(stockMode: value ? StockMode.optimistic : StockMode.pessimistic));
   }
 
   void _handleBackupChanged(bool value) {
-    sendUpdates(config.optimism, value ? BackupMode.enabled : BackupMode.disabled, config.showGrid);
+    sendUpdates(config.configuration.copyWith(backupMode: value ? BackupMode.enabled : BackupMode.disabled));
   }
 
   void _handleShowGridChanged(bool value) {
-    sendUpdates(config.optimism, config.backup, value);
+    sendUpdates(config.configuration.copyWith(showGrid: value));
   }
 
   void _confirmOptimismChange() {
-    switch (config.optimism) {
+    switch (config.configuration.stockMode) {
       case StockMode.optimistic:
         _handleOptimismChanged(false);
         break;
@@ -66,13 +58,9 @@ class StockSettingsState extends State<StockSettings> {
     }
   }
 
-  void sendUpdates(StockMode optimism, BackupMode backup, bool showGrid) {
+  void sendUpdates(StockConfiguration value) {
     if (config.updater != null)
-      config.updater(
-        optimism: optimism,
-        backup: backup,
-        showGrid: showGrid
-      );
+      config.updater(value);
   }
 
   Widget buildToolBar(BuildContext context) {
@@ -82,8 +70,6 @@ class StockSettingsState extends State<StockSettings> {
   }
 
   Widget buildSettingsPane(BuildContext context) {
-    // TODO(ianh): Once we have the gesture API hooked up, fix https://github.com/domokit/mojo/issues/281
-    // (whereby tapping the widgets below causes both the widget and the menu item to fire their callbacks)
     List<Widget> rows = <Widget>[
       new DrawerItem(
         icon: 'action/thumb_up',
@@ -91,18 +77,18 @@ class StockSettingsState extends State<StockSettings> {
         child: new Row(<Widget>[
           new Flexible(child: new Text('Everything is awesome')),
           new Checkbox(
-            value: config.optimism == StockMode.optimistic,
+            value: config.configuration.stockMode == StockMode.optimistic,
             onChanged: (bool value) => _confirmOptimismChange()
           ),
         ])
       ),
       new DrawerItem(
         icon: 'action/backup',
-        onPressed: () { _handleBackupChanged(!(config.backup == BackupMode.enabled)); },
+        onPressed: () { _handleBackupChanged(!(config.configuration.backupMode == BackupMode.enabled)); },
         child: new Row(<Widget>[
           new Flexible(child: new Text('Back up stock list to the cloud')),
           new Switch(
-            value: config.backup == BackupMode.enabled,
+            value: config.configuration.backupMode == BackupMode.enabled,
             onChanged: _handleBackupChanged
           ),
         ])
@@ -113,11 +99,11 @@ class StockSettingsState extends State<StockSettings> {
       rows.add(
         new DrawerItem(
           icon: 'editor/border_clear',
-          onPressed: () { _handleShowGridChanged(!config.showGrid); },
+          onPressed: () { _handleShowGridChanged(!config.configuration.showGrid); },
           child: new Row(<Widget>[
             new Flexible(child: new Text('Show material grid (for debugging)')),
             new Switch(
-              value: config.showGrid,
+              value: config.configuration.showGrid,
               onChanged: _handleShowGridChanged
             ),
           ])

examples/stocks/lib/stock_types.dart

@@ -6,3 +6,31 @@ part of stocks;
 
 enum StockMode { optimistic, pessimistic }
 enum BackupMode { enabled, disabled }
+
+class StockConfiguration {
+  StockConfiguration({
+    this.stockMode,
+    this.backupMode,
+    this.showGrid
+  }) {
+    assert(stockMode != null);
+    assert(backupMode != null);
+    assert(showGrid != null);
+  }
+
+  final StockMode stockMode;
+  final BackupMode backupMode;
+  final bool showGrid;
+
+  StockConfiguration copyWith({
+    StockMode stockMode,
+    BackupMode backupMode,
+    bool showGrid
+  }) {
+    return new StockConfiguration(
+      stockMode: stockMode ?? this.stockMode,
+      backupMode: backupMode ?? this.backupMode,
+      showGrid: showGrid ?? this.showGrid
+    );
+  }
+}