add the $ alias for value

add autosave feature
handle and edge case where value was updated during flutter widget build phase, and shared value subscribed widgets were not notified later
update example app
0.3.0

Author: devxpy

README.md

@@ -35,8 +35,8 @@ class MyWidgetState extends State<MyWidget> {
     @override
     Widget build(BuildContext context) {
 
-        // supply [counter] the `BuildContext` to rebuild widget
-        counterValue = counter.of(context);
+        // The .of(context) bit makes this widget rebuild everytime counter is changed
+        int counterValue = counter.of(context);
 
         return Text("Counter: $counterValue");
     }
@@ -59,5 +59,3 @@ await counter.load();
 ## Efficiency
 
 Shared value is smart enough to only rebuild the widget that is using the shared value that was updated. No more, no less.
-
-

example/android/app/src/main/AndroidManifest.xml

@@ -7,7 +7,6 @@
          additional functionality it is fine to subclass or reimplement
          FlutterApplication and put your custom class here. -->
     <application
-        android:name="io.flutter.app.FlutterApplication"
         android:label="example"
         android:icon="@mipmap/ic_launcher">
         <activity
@@ -25,9 +24,12 @@
                 android:name="io.flutter.app.android.SplashScreenUntilFirstFrame"
                 android:value="true" />
             <intent-filter>
-                <action android:name="android.intent.action.MAIN"/>
-                <category android:name="android.intent.category.LAUNCHER"/>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <meta-data
+            android:name="flutterEmbedding"
+            android:value="2" />
     </application>
 </manifest>

example/android/app/src/main/kotlin/scientifichackers/com/example/MainActivity.kt

@@ -1,13 +1,5 @@
 package scientifichackers.com.example
 
-import android.os.Bundle
+import io.flutter.embedding.android.FlutterActivity
 
-import io.flutter.app.FlutterActivity
-import io.flutter.plugins.GeneratedPluginRegistrant
-
-class MainActivity: FlutterActivity() {
-  override fun onCreate(savedInstanceState: Bundle?) {
-    super.onCreate(savedInstanceState)
-    GeneratedPluginRegistrant.registerWith(this)
-  }
-}
+class MainActivity : FlutterActivity() {}

example/lib/main.dart

@@ -1,14 +1,15 @@
 import 'package:flutter/material.dart';
 import 'package:shared_value/shared_value.dart';
 
-// This SharedValue can be shared from any number of widgets.
-final counter = SharedValue(
+// This global SharedValue can be shared across the entire app
+final SharedValue<int> counter = SharedValue(
   value: 0, // initial value
   key: "counter", // disk storage key for shared_preferences
+  autosave: true, // autosave to shared prefs when value changes
 );
 
-void main() {
-  runApp(SharedValue.wrapApp(MyApp()));
+Future<void> main() async {
+  runApp(SharedValue.wrapApp(MyApp())); //  don't forget this!
 }
 
 class MyApp extends StatelessWidget {
@@ -39,7 +40,7 @@ class _MyHomePageState extends State<MyHomePage> {
   @override
   Widget build(BuildContext context) {
     // The .of(context) bit makes this widget rebuild everytime counter is changed
-    var counterValue = counter.of(context);
+    int counterValue = counter.of(context);
 
     return Scaffold(
       appBar: AppBar(
@@ -71,16 +72,11 @@ class _MyHomePageState extends State<MyHomePage> {
   void initState() {
     super.initState();
 
-    // Load the previously stored value of counter to disk using shared_preferences
-    counter.load();
+    counter.load(); // load previous value from shared prefs
   }
 
   Future<void> _incrementCounter() async {
-    setState(() {});
     // update counter value and rebuild all widgets using that value
     counter.update((value) => value + 1);
-
-    // Save the internal value of counter to disk using shared_preferences
-    await counter.save();
   }
 }

example/pubspec.lock

@@ -7,42 +7,42 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.4.2"
+    version: "2.5.0-nullsafety.1"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.0"
+    version: "2.1.0-nullsafety.1"
   characters:
     dependency: transitive
     description:
       name: characters
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.0"
+    version: "1.1.0-nullsafety.3"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.3"
+    version: "1.2.0-nullsafety.1"
   clock:
     dependency: transitive
     description:
       name: clock
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.1"
+    version: "1.1.0-nullsafety.1"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.13"
+    version: "1.15.0-nullsafety.3"
   cupertino_icons:
     dependency: "direct main"
     description:
@@ -56,7 +56,7 @@ packages:
       name: fake_async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0-nullsafety.1"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -78,21 +78,21 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.8"
+    version: "0.12.10-nullsafety.1"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.8"
+    version: "1.3.0-nullsafety.3"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.7.0"
+    version: "1.8.0-nullsafety.1"
   shared_preferences:
     dependency: transitive
     description:
@@ -127,7 +127,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.1.5"
+    version: "0.2.0"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -139,56 +139,56 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.7.0"
+    version: "1.8.0-nullsafety.2"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.5"
+    version: "1.10.0-nullsafety.1"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.0"
+    version: "2.1.0-nullsafety.1"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.5"
+    version: "1.1.0-nullsafety.1"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0-nullsafety.1"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.17"
+    version: "0.2.19-nullsafety.2"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0"
+    version: "1.3.0-nullsafety.3"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
+    version: "2.1.0-nullsafety.3"
 sdks:
-  dart: ">=2.9.0-14.0.dev <3.0.0"
+  dart: ">=2.10.0-110 <2.11.0"
   flutter: ">=1.12.13+hotfix.4 <2.0.0"

lib/manager_widget.dart

@@ -23,9 +23,14 @@ class StateManagerWidget extends StatefulWidget {
 
 class StateManagerWidgetState extends State<StateManagerWidget> {
   void rebuild() {
+    if (!mounted) return;
     try {
       setState(() {});
-    } catch (_) {}
+    } catch (_) {
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        setState(() {});
+      });
+    }
   }
 
   @override

lib/shared_value.dart

@@ -32,11 +32,22 @@ class SharedValue<T> {
   /// The key to use for storing this value in shared preferences.
   final String key;
 
-  SharedValue({this.key, T value}) {
+  /// automatically save to shared preferences when the value changes
+  final bool autosave;
+
+  SharedValue({this.key, T value, this.autosave = false}) {
     _value = value;
     _update(rebuild: false);
   }
 
+  /// Alias for [value]
+  T get $ => value;
+
+  /// Alias for [value]
+  set $(T newValue) {
+    value = newValue;
+  }
+
   /// The value held by this state.
   T get value => _value;
 
@@ -110,12 +121,17 @@ class SharedValue<T> {
 
     // add value to stream
     _controller?.add(value);
+
+    if (autosave) {
+      save();
+    }
   }
 
   /// Try to load the value stored at [key] in shared preferences.
   /// If no value is found, return immediately.
   /// Else, udpdate [value] and rebuild dependent widgets if it changed.
   Future<void> load() async {
+    assert(key != null);
     var pref = await SharedPreferences.getInstance();
     var str = pref.getString(key);
     if (str == null) return;
@@ -124,16 +140,17 @@ class SharedValue<T> {
 
   /// Store the current [value] at [key] in shared preferences.
   Future<void> save() async {
+    assert(key != null);
     var pref = await SharedPreferences.getInstance();
     await pref.setString(key, serialize(_value));
   }
 
-  /// serialize [obj] of type [T].
+  /// serialize [obj] of type [T] for shared preferences.
   String serialize(T obj) {
     return jsonEncode(obj);
   }
 
-  /// desrialize [str] to an obj of type [T].
+  /// desrialize [str] to an obj of type [T] for shared preferences.
   T deserialize(String str) {
     return jsonDecode(str) as T;
   }