(watch)表达式没有计算出一个函数，所以它不能被调用

Question

我正在尝试为我的 flutter 项目设置一个主题，如果您能告诉我另一种方法，我将不胜感激。

import 'package:firebase_analytics/firebase_analytics.dart';
import 'package:firebase_analytics/observer.dart';
import 'package:flutter/material.dart';
import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:picpuzzle/routes/route_name.dart';
import 'package:picpuzzle/widgets/login/login_screen.dart';
import 'package:picpuzzle/widgets/main/main_page.dart';
import 'package:picpuzzle/widgets/puzzle/puzzle_list_page.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';
import 'common/constants.dart';

/// use for DarkMode,not sync  with system
final DarkModeProvider = StateProvider((ref) => false);

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  static FirebaseAnalytics analytics = FirebaseAnalytics.instance;
  static FirebaseAnalyticsObserver observer =
      FirebaseAnalyticsObserver(analytics: analytics);

  void initApp(BuildContext context) {}

  @override
  Widget build(BuildContext context) {
    /// init
    initApp(context);
    return Consumer(
      builder: (context, watch, _) {
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          localizationsDelegates: [
            AppLocalizations.delegate, // Add this line
            GlobalMaterialLocalizations.delegate,
            GlobalWidgetsLocalizations.delegate,
            GlobalCupertinoLocalizations.delegate,
          ],
          supportedLocales: [
            const Locale('en', ''), // English, no country code
            const Locale('ja', ''), // Japanese, no country code
          ],
          title: 'Pic Puzzle',
          initialRoute: RouteName.Login,
          routes: {
            RouteName.Login: (context) => LoginScreen(),
            RouteName.Main: (context) => MainPage(),
            RouteName.Home: (context) => PuzzleListPage(),
          },
          theme: watch(DarkModeProvider).state ? darkTheme : lightTheme,
          // darkTheme: darkTheme,
        );
      },
    );
  }
}

但是因为这个

所以无法做到

lib/my_app.dart:49:23: Error: The method 'call' isn't defined for the class 'WidgetRef'. - 'WidgetRef' is from 'package:flutter_riverpod/src/consumer.dart' ('../Documents/flutter_windows_2.8.1-stable/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_riverpod-1.0.3/lib/src/consumer.dart'). Try correcting the name to the name of an existing method, or defining a method named 'call'. theme: watch(DarkModeProvider).state ? darkTheme : lightTheme,

Answer 1

这部分

theme: watch(DarkModeProvider).state ? darkTheme : lightTheme,

应改为：

theme: watch.watch(DarkModeProvider.state).state ? darkTheme : lightTheme,

(watch)表达式没有计算出一个函数，所以它不能被调用

(watch)The expression doesn't evaluate to a function, so it can't be invoked

flutter

flutter-layout