Upgrade to Flutter 2 and null-safety

.gitignore

@@ -1,12 +1,14 @@
 .atom/
 .idea/
 *.iml
+.vscode/
 
 # dart
 .packages
 .pub
 packages
 pubspec.lock
+.dart_tool/
 
 # flutter
 build/

example/ios/.gitignore

@@ -38,5 +38,6 @@ Icon?
 /Flutter/Flutter.framework
 /Flutter/Generated.xcconfig
 /ServiceDefinitions.json
+/Flutter/flutter_export_environment.sh
 
 Pods/

example/ios/Flutter/AppFrameworkInfo.plist

@@ -25,6 +25,6 @@
     <string>arm64</string>
   </array>
   <key>MinimumOSVersion</key>
-  <string>8.0</string>
+  <string>9.0</string>
 </dict>
 </plist>

example/ios/Runner.xcodeproj/project.pbxproj

@@ -8,12 +8,7 @@
 
 /* Begin PBXBuildFile section */
 		1498D2341E8E89220040F4C2 /* GeneratedPluginRegistrant.m in Sources */ = {isa = PBXBuildFile; fileRef = 1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */; };
-		2D5378261FAA1A9400D5DBA9 /* flutter_assets in Resources */ = {isa = PBXBuildFile; fileRef = 2D5378251FAA1A9400D5DBA9 /* flutter_assets */; };
 		3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };
-		3B80C3941E831B6300D905FE /* App.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 3B80C3931E831B6300D905FE /* App.framework */; };
-		3B80C3951E831B6300D905FE /* App.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 3B80C3931E831B6300D905FE /* App.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
-		9705A1C61CF904A100538489 /* Flutter.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 9740EEBA1CF902C7004384FC /* Flutter.framework */; };
-		9705A1C71CF904A300538489 /* Flutter.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 9740EEBA1CF902C7004384FC /* Flutter.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		9740EEB41CF90195004384FC /* Debug.xcconfig in Resources */ = {isa = PBXBuildFile; fileRef = 9740EEB21CF90195004384FC /* Debug.xcconfig */; };
 		9740EEB51CF90195004384FC /* Generated.xcconfig in Resources */ = {isa = PBXBuildFile; fileRef = 9740EEB31CF90195004384FC /* Generated.xcconfig */; };
 		978B8F6F1D3862AE00F588F7 /* AppDelegate.m in Sources */ = {isa = PBXBuildFile; fileRef = 7AFFD8EE1D35381100E5BB4D /* AppDelegate.m */; };
@@ -30,8 +25,6 @@
 			dstPath = "";
 			dstSubfolderSpec = 10;
 			files = (
-				3B80C3951E831B6300D905FE /* App.framework in Embed Frameworks */,
-				9705A1C71CF904A300538489 /* Flutter.framework in Embed Frameworks */,
 			);
 			name = "Embed Frameworks";
 			runOnlyForDeploymentPostprocessing = 0;
@@ -41,15 +34,12 @@
 /* Begin PBXFileReference section */
 		1498D2321E8E86230040F4C2 /* GeneratedPluginRegistrant.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GeneratedPluginRegistrant.h; sourceTree = "<group>"; };
 		1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GeneratedPluginRegistrant.m; sourceTree = "<group>"; };
-		2D5378251FAA1A9400D5DBA9 /* flutter_assets */ = {isa = PBXFileReference; lastKnownFileType = folder; name = flutter_assets; path = Flutter/flutter_assets; sourceTree = SOURCE_ROOT; };
 		3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = AppFrameworkInfo.plist; path = Flutter/AppFrameworkInfo.plist; sourceTree = "<group>"; };
-		3B80C3931E831B6300D905FE /* App.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = App.framework; path = Flutter/App.framework; sourceTree = "<group>"; };
 		7AFA3C8E1D35360C0083082E /* Release.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; name = Release.xcconfig; path = Flutter/Release.xcconfig; sourceTree = "<group>"; };
 		7AFFD8ED1D35381100E5BB4D /* AppDelegate.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = AppDelegate.h; sourceTree = "<group>"; };
 		7AFFD8EE1D35381100E5BB4D /* AppDelegate.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = AppDelegate.m; sourceTree = "<group>"; };
 		9740EEB21CF90195004384FC /* Debug.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Debug.xcconfig; path = Flutter/Debug.xcconfig; sourceTree = "<group>"; };
 		9740EEB31CF90195004384FC /* Generated.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Generated.xcconfig; path = Flutter/Generated.xcconfig; sourceTree = "<group>"; };
-		9740EEBA1CF902C7004384FC /* Flutter.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = Flutter.framework; path = Flutter/Flutter.framework; sourceTree = "<group>"; };
 		97C146EE1CF9000F007C117D /* Runner.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Runner.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		97C146F21CF9000F007C117D /* main.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = main.m; sourceTree = "<group>"; };
 		97C146FB1CF9000F007C117D /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/Main.storyboard; sourceTree = "<group>"; };
@@ -63,8 +53,6 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				9705A1C61CF904A100538489 /* Flutter.framework in Frameworks */,
-				3B80C3941E831B6300D905FE /* App.framework in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -74,10 +62,7 @@
 		9740EEB11CF90186004384FC /* Flutter */ = {
 			isa = PBXGroup;
 			children = (
-				2D5378251FAA1A9400D5DBA9 /* flutter_assets */,
-				3B80C3931E831B6300D905FE /* App.framework */,
 				3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */,
-				9740EEBA1CF902C7004384FC /* Flutter.framework */,
 				9740EEB21CF90195004384FC /* Debug.xcconfig */,
 				7AFA3C8E1D35360C0083082E /* Release.xcconfig */,
 				9740EEB31CF90195004384FC /* Generated.xcconfig */,
@@ -192,7 +177,6 @@
 				3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */,
 				9740EEB41CF90195004384FC /* Debug.xcconfig in Resources */,
 				97C146FE1CF9000F007C117D /* Assets.xcassets in Resources */,
-				2D5378261FAA1A9400D5DBA9 /* flutter_assets in Resources */,
 				97C146FC1CF9000F007C117D /* Main.storyboard in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -212,7 +196,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "/bin/sh \"$FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh\" thin";
+			shellScript = "/bin/sh \"$FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh\" embed_and_thin";
 		};
 		9740EEB61CF901F6004384FC /* Run Script */ = {
 			isa = PBXShellScriptBuildPhase;
@@ -265,7 +249,6 @@
 /* Begin XCBuildConfiguration section */
 		97C147031CF9000F007C117D /* Debug */ = {
 			isa = XCBuildConfiguration;
-			baseConfigurationReference = 9740EEB21CF90195004384FC /* Debug.xcconfig */;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				CLANG_ANALYZER_NONNULL = YES;
@@ -309,7 +292,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
@@ -319,7 +302,6 @@
 		};
 		97C147041CF9000F007C117D /* Release */ = {
 			isa = XCBuildConfiguration;
-			baseConfigurationReference = 7AFA3C8E1D35360C0083082E /* Release.xcconfig */;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				CLANG_ANALYZER_NONNULL = YES;
@@ -357,7 +339,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				TARGETED_DEVICE_FAMILY = "1,2";

example/lib/main.dart

@@ -16,7 +16,7 @@ void main() {
 
 class ChatScreen extends StatefulWidget {
   /// Creates a widget that watches stores.
-  ChatScreen({Key key}) : super(key: key);
+  ChatScreen({Key? key}) : super(key: key);
 
   @override
   ChatScreenState createState() => new ChatScreenState();
@@ -33,8 +33,8 @@ class ChatScreen extends StatefulWidget {
 class ChatScreenState extends State<ChatScreen>
     with StoreWatcherMixin<ChatScreen> {
   // Never write to these stores directly. Use Actions.
-  ChatMessageStore messageStore;
-  ChatUserStore chatUserStore;
+  late ChatMessageStore messageStore;
+  late ChatUserStore chatUserStore;
 
   final TextEditingController msgController = new TextEditingController();
 
@@ -52,23 +52,24 @@ class ChatScreenState extends State<ChatScreen>
 
     // Demonstrates using a custom change handler.
     messageStore =
-        listenToStore(messageStoreToken, handleChatMessageStoreChanged);
+        listenToStore(messageStoreToken, handleChatMessageStoreChanged)
+            as ChatMessageStore;
 
     // Demonstrates using the default handler, which just calls setState().
-    chatUserStore = listenToStore(userStoreToken);
+    chatUserStore = listenToStore(userStoreToken) as ChatUserStore;
   }
 
   void handleChatMessageStoreChanged(Store store) {
-    ChatMessageStore messageStore = store;
+    ChatMessageStore messageStore = store as ChatMessageStore;
     if (messageStore.currentMessage.isEmpty) {
-        msgController.clear();
+      msgController.clear();
     }
     setState(() {});
   }
 
   Widget _buildTextComposer(BuildContext context, ChatMessageStore messageStore,
       ChatUserStore userStore) {
-    final ValueChanged<String> commitMessage = (String _) {
+    final ValueChanged<String?> commitMessage = (String? _) {
       commitCurrentMessageAction(userStore.me);
     };
 
@@ -122,8 +123,8 @@ class ChatMessageListItem extends StatefulWidget {
 
 class ChatMessageListItemState extends State<ChatMessageListItem>
     with SingleTickerProviderStateMixin {
-  AnimationController _animationController;
-  Animation<double> _animation;
+  late AnimationController _animationController;
+  late Animation<double> _animation;
 
   @override
   void initState() {

example/lib/stores.dart

@@ -4,29 +4,29 @@
 
 import 'dart:math' show Random;
 
-import 'package:flutter/material.dart';
+import 'package:flutter/material.dart' show Color, Colors;
 import 'package:flutter_flux/flutter_flux.dart';
 
 class ChatUser {
-  ChatUser({this.name, this.color});
+  ChatUser({required this.name, required this.color});
   final String name;
   final Color color;
 }
 
 class ChatMessage {
-  ChatMessage({this.sender, this.text});
+  ChatMessage({required this.sender, required this.text});
   final ChatUser sender;
   final String text;
 }
 
 class ChatMessageStore extends Store {
   ChatMessageStore() {
-    triggerOnAction(setCurrentMessageAction, (String value) {
-      _currentMessage = value;
+    triggerOnAction(setCurrentMessageAction, (String? value) {
+      _currentMessage = value ?? '';
     });
-    triggerOnAction(commitCurrentMessageAction, (ChatUser me) {
+    triggerOnAction(commitCurrentMessageAction, (ChatUser? me) {
       final ChatMessage message =
-          new ChatMessage(sender: me, text: _currentMessage);
+          new ChatMessage(sender: me!, text: _currentMessage);
       _messages.add(message);
       _currentMessage = '';
     });
@@ -46,12 +46,12 @@ class ChatUserStore extends Store {
   ChatUserStore() {
     final String name = "Guest${new Random().nextInt(1000)}";
     final Color color =
-        Colors.accents[new Random().nextInt(Colors.accents.length)][700];
+        Colors.accents[new Random().nextInt(Colors.accents.length)][700]!;
     _me = new ChatUser(name: name, color: color);
     // This store does not currently handle any actions.
   }
 
-  ChatUser _me;
+  late ChatUser _me;
   ChatUser get me => _me;
 }
 

example/pubspec.yaml

@@ -13,3 +13,6 @@ dev_dependencies:
 
 flutter:
   uses-material-design: true
+
+environment:
+  sdk: '>=2.12.0 <3.0.0'

lib/src/action.dart

@@ -41,12 +41,12 @@ typedef void OnData<T>(T event);
 /// when a consumer needs to check state changes immediately after invoking an
 /// action.
 ///
-class Action<T> implements Function {
-  List<OnData<T>> _listeners = <OnData<T>>[];
+class Action<T> {
+  List<OnData<T?>> _listeners = <OnData<T?>>[];
 
   /// Dispatch this [Action] to all listeners. If a payload is supplied, it will
   /// be passed to each listener's callback, otherwise null will be passed.
-  Future<List<dynamic>> call([T payload]) {
+  Future<List<dynamic>> call([T? payload]) {
     // Invoke all listeners in a microtask to enable waiting on futures. The
     // microtask queue is emptied before the event loop continues. This ensures
     // synchronous listeners are invoked in the current tick of the event loop
@@ -60,7 +60,7 @@ class Action<T> implements Function {
     // for stream-based actions vs. 0.14 ms for this action implementation.
     return Future.wait<dynamic>(
       _listeners.map(
-        (OnData<T> l) => new Future<dynamic>.microtask(() => l(payload))
+        (OnData<T?> l) => new Future<dynamic>.microtask(() => l(payload)),
       ),
     );
   }
@@ -74,7 +74,7 @@ class Action<T> implements Function {
   /// dispatched. A payload of type [T] will be passed to the callback if
   /// supplied at dispatch time, otherwise null will be passed. Returns an
   /// [ActionSubscription] which provides means to cancel the subscription.
-  ActionSubscription listen(OnData<T> onData) {
+  ActionSubscription listen(OnData<T?> onData) {
     _listeners.add(onData);
     return new ActionSubscription(() => _listeners.remove(onData));
   }
@@ -84,14 +84,14 @@ typedef void _OnCancel();
 
 /// A subscription used to cancel registered listeners to an [Action].
 class ActionSubscription {
-  final _OnCancel _onCancel;
+  final _OnCancel? _onCancel;
 
   ActionSubscription(this._onCancel);
 
   /// Cancel this subscription to an [Action]
   void cancel() {
     if (_onCancel != null) {
-      _onCancel();
+      _onCancel!();
     }
   }
 }

lib/src/store.dart

@@ -48,19 +48,20 @@ class Store {
   /// As an example, [transformer] could be used to throttle the number of
   /// triggers this [Store] emits for state that may update extremely frequently
   /// (like scroll position).
-  Store.withTransformer(StreamTransformer<dynamic, dynamic> transformer) {
+  Store.withTransformer(StreamTransformer<Store, dynamic> transformer) {
     _streamController = new StreamController<Store>();
 
     // apply a transform to the stream if supplied
-    _stream =
-        _streamController.stream.transform<dynamic>(transformer).asBroadcastStream();
+    _stream = _streamController.stream
+        .transform<dynamic>(transformer)
+        .asBroadcastStream() as Stream<Store>;
   }
 
   /// Stream controller for [_stream]. Used by [trigger].
-  StreamController<Store> _streamController;
+  late StreamController<Store> _streamController;
 
   /// Broadcast stream of "data updated" events. Listened to in [listen].
-  Stream<Store> _stream;
+  late Stream<Store> _stream;
 
   void dispose() {
     _streamController.close();
@@ -79,10 +80,9 @@ class Store {
   /// A convenience method for listening to an [action] and triggering
   /// automatically. The callback doesn't call return, so the return
   /// type of onAction is null.
-  void triggerOnAction<T>(Action<T> action,
-      [dynamic onAction(T payload)]) {
+  void triggerOnAction<T>(Action<T> action, [dynamic onAction(T? payload)?]) {
     if (onAction != null) {
-      action.listen((T payload) async {
+      action.listen((T? payload) async {
         await onAction(payload);
         trigger();
       });
@@ -102,7 +102,6 @@ class Store {
   /// void (null) or true.
   void triggerOnConditionalAction<T>(
       Action<T> action, FutureOr<bool> onAction(T payload)) {
-    assert(action != null);
     action.listen((dynamic payload) async {
       // Action functions must return bool, or a Future<bool>.
       dynamic result = onAction(payload);
@@ -123,8 +122,12 @@ class Store {
   /// Each time this `Store` triggers (by calling [trigger]), indicating that
   /// data has been mutated, [onData] will be called.
   StreamSubscription<Store> listen(void onData(Store event),
-      {Function onError, void onDone(), bool cancelOnError}) {
-    return _stream.listen(onData,
-        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
+    return _stream.listen(
+      onData,
+      onError: onError,
+      onDone: onDone,
+      cancelOnError: cancelOnError,
+    );
   }
 }