chimon2000 · May 3, 2023 18:58 · May 3, 2023 · May 3, 2023 · May 3, 2023 · May 3, 2023
diff --git a/main.dart b/main.dart
@@ -88,7 +88,7 @@ class CounterScope extends InheritedNotifier<CounterController> {
         context.dependOnInheritedWidgetOfExactType<CounterScope>();
 
     assert(result != null, 'No CounterScope found in context');
-    assert(result!.notifier != null, 'No CounterScope found in context');
+    assert(result!.notifier != null, 'No CounterController found in context');
 
     return result!.notifier!;
   }

diff --git a/main.dart b/main.dart
@@ -49,6 +49,33 @@ class HomePage extends StatelessWidget {
   }
 }
 
+class CounterDisplay extends StatelessWidget {
+  const CounterDisplay({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Text(
+      '${CounterScope.of(context).value}',
+      style: Theme.of(context).textTheme.headlineMedium,
+    );
+  }
+}
+
+class IncrementButton extends StatelessWidget {
+  const IncrementButton({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Builder(
+      builder: (context) => FloatingActionButton(
+        onPressed: CounterScope.of(context).increment,
+        tooltip: 'Increment',
+        child: const Icon(Icons.add),
+      ),
+    );
+  }
+}
+
 class CounterScope extends InheritedNotifier<CounterController> {
   const CounterScope({
     super.key,
@@ -78,30 +105,3 @@ class CounterController extends ValueNotifier<int> {
     value = value - 1;
   }
 }
-
-class CounterDisplay extends StatelessWidget {
-  const CounterDisplay({super.key});
-
-  @override
-  Widget build(BuildContext context) {
-    return Text(
-      '${CounterScope.of(context).value}',
-      style: Theme.of(context).textTheme.headlineMedium,
-    );
-  }
-}
-
-class IncrementButton extends StatelessWidget {
-  const IncrementButton({super.key});
-
-  @override
-  Widget build(BuildContext context) {
-    return Builder(
-      builder: (context) => FloatingActionButton(
-        onPressed: CounterScope.of(context).increment,
-        tooltip: 'Increment',
-        child: const Icon(Icons.add),
-      ),
-    );
-  }
-}
diff --git a/main.dart b/main.dart
@@ -1,12 +1,8 @@
-// Copyright (c) 2019, 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.
-
 import 'package:flutter/material.dart';
 
-void main() => runApp(MyApp());
+void main() => runApp(CounterApp());
 
-class MyApp extends StatelessWidget {
+class CounterApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -15,13 +11,13 @@ class MyApp extends StatelessWidget {
       theme: ThemeData(
         primarySwatch: Colors.blue,
       ),
-      home: const MyHomePage(title: 'Flutter Demo Home Page'),
+      home: const HomePage(title: 'Flutter Demo Home Page'),
     );
   }
 }
 
-class MyHomePage extends StatelessWidget {
-  const MyHomePage({
+class HomePage extends StatelessWidget {
+  const HomePage({
     Key? key,
     required this.title,
   }) : super(key: key);
@@ -30,7 +26,6 @@ class MyHomePage extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-
     return CounterScope(
       notifier: CounterController(),
       child: Scaffold(
@@ -48,13 +43,7 @@ class MyHomePage extends StatelessWidget {
             ],
           ),
         ),
-        floatingActionButton: Builder(
-          builder: (context) => FloatingActionButton(
-            onPressed: CounterScope.of(context).increment,
-            tooltip: 'Increment',
-            child: const Icon(Icons.add),
-          ),
-        ),
+        floatingActionButton: const IncrementButton(),
       ),
     );
   }
@@ -72,7 +61,7 @@ class CounterScope extends InheritedNotifier<CounterController> {
         context.dependOnInheritedWidgetOfExactType<CounterScope>();
 
     assert(result != null, 'No CounterScope found in context');
-    assert(result!.notifier != null, 'No CounterController found in context');
+    assert(result!.notifier != null, 'No CounterScope found in context');
 
     return result!.notifier!;
   }
@@ -101,3 +90,18 @@ class CounterDisplay extends StatelessWidget {
     );
   }
 }
+
+class IncrementButton extends StatelessWidget {
+  const IncrementButton({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Builder(
+      builder: (context) => FloatingActionButton(
+        onPressed: CounterScope.of(context).increment,
+        tooltip: 'Increment',
+        child: const Icon(Icons.add),
+      ),
+    );
+  }
+}
diff --git a/main.dart b/main.dart
@@ -72,7 +72,7 @@ class CounterScope extends InheritedNotifier<CounterController> {
         context.dependOnInheritedWidgetOfExactType<CounterScope>();
 
     assert(result != null, 'No CounterScope found in context');
-    assert(result!.notifier != null, 'No CounterScope found in context');
+    assert(result!.notifier != null, 'No CounterController found in context');
 
     return result!.notifier!;
   }

diff --git a/main.dart b/main.dart
@@ -0,0 +1,103 @@
+// Copyright (c) 2019, 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.
+
+import 'package:flutter/material.dart';
+
+void main() => runApp(MyApp());
+
+class MyApp extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Demo',
+      debugShowCheckedModeBanner: false,
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      home: const MyHomePage(title: 'Flutter Demo Home Page'),
+    );
+  }
+}
+
+class MyHomePage extends StatelessWidget {
+  const MyHomePage({
+    Key? key,
+    required this.title,
+  }) : super(key: key);
+
+  final String title;
+
+  @override
+  Widget build(BuildContext context) {
+
+    return CounterScope(
+      notifier: CounterController(),
+      child: Scaffold(
+        appBar: AppBar(
+          title: Text(title),
+        ),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: const [
+              Text(
+                'You have pushed the button this many times:',
+              ),
+              CounterDisplay(),
+            ],
+          ),
+        ),
+        floatingActionButton: Builder(
+          builder: (context) => FloatingActionButton(
+            onPressed: CounterScope.of(context).increment,
+            tooltip: 'Increment',
+            child: const Icon(Icons.add),
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class CounterScope extends InheritedNotifier<CounterController> {
+  const CounterScope({
+    super.key,
+    required super.child,
+    super.notifier,
+  });
+
+  static CounterController of(BuildContext context) {
+    final CounterScope? result =
+        context.dependOnInheritedWidgetOfExactType<CounterScope>();
+
+    assert(result != null, 'No CounterScope found in context');
+    assert(result!.notifier != null, 'No CounterScope found in context');
+
+    return result!.notifier!;
+  }
+}
+
+class CounterController extends ValueNotifier<int> {
+  CounterController([int initialValue = 0]) : super(initialValue);
+
+  void increment() {
+    value = value + 1;
+  }
+
+  void decrement() {
+    value = value - 1;
+  }
+}
+
+class CounterDisplay extends StatelessWidget {
+  const CounterDisplay({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Text(
+      '${CounterScope.of(context).value}',
+      style: Theme.of(context).textTheme.headlineMedium,
+    );
+  }
+}