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July 29, 2024 15:17
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BadFL Example Code (impl/event_center)
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| import 'package:flutter/material.dart'; | |
| void main() { | |
| runApp(const MyApp()); | |
| } | |
| class MyApp extends StatelessWidget { | |
| const MyApp({super.key}); | |
| void handler1(dynamic eventData) { | |
| print('in handler1: $eventData'); | |
| } | |
| void handler2(dynamic eventData) { | |
| print('in handler2: $eventData'); | |
| } | |
| @override | |
| Widget build(BuildContext context) { | |
| return MaterialApp( | |
| home: Scaffold( | |
| body: ListView( | |
| children: [ | |
| ElevatedButton( | |
| onPressed: () => BadEventCenter.listen('ev1', handler1), | |
| child: const Text('add handler1'), | |
| ), | |
| ElevatedButton( | |
| onPressed: () => BadEventCenter.listen('ev1', handler2), | |
| child: const Text('add handler2'), | |
| ), | |
| ElevatedButton( | |
| onPressed: () => BadEventCenter.unListen('ev1', handler2), | |
| child: const Text('remove handler2'), | |
| ), | |
| ElevatedButton( | |
| onPressed: () => BadEventCenter.unListen('ev1', handler1), | |
| child: const Text('remove handler1'), | |
| ), | |
| ElevatedButton( | |
| onPressed: () => BadEventCenter.unListen('ev1'), | |
| child: const Text('remove all handler on ev1'), | |
| ), | |
| ElevatedButton( | |
| onPressed: () => BadEventCenter.unListenAll(), | |
| child: const Text('remove all handler'), | |
| ), | |
| ElevatedButton( | |
| onPressed: () => BadEventCenter.trigger('ev1', 'data'), | |
| child: const Text('trigger ev1'), | |
| ), | |
| ], | |
| ), | |
| ), | |
| ); | |
| } | |
| } | |
| typedef EventHandler = void Function(dynamic eventData); | |
| typedef StopListen = void Function(); | |
| /// `impl::event_center`: event center implementation | |
| abstract class BadEventCenter { | |
| static final Map<String, Set<EventHandler>> _handlers = {}; | |
| /// add a [handler] on [eventName] | |
| static StopListen listen(String eventName, EventHandler handler) { | |
| var handlers = _handlers[eventName]; | |
| if (handlers == null) { | |
| _handlers[eventName] = {handler}; | |
| } else { | |
| handlers.add(handler); | |
| } | |
| return () { | |
| handlers?.remove(handler); | |
| }; | |
| } | |
| /// remove specific [handler] on [eventName], | |
| /// if [handler] is null, remove all handlers on [eventName] | |
| static void unListen(String eventName, [EventHandler? handler]) { | |
| if (handler == null) { | |
| _handlers.remove(eventName); | |
| } else { | |
| _handlers[eventName]?.remove(handler); | |
| } | |
| } | |
| /// remove all handlers on all events | |
| static void unListenAll() { | |
| _handlers.clear(); | |
| } | |
| /// trigger all handlers on [eventName] with [eventData] | |
| static void trigger(String evName, [dynamic eventData]) { | |
| var handlers = _handlers[evName]; | |
| if (handlers == null) { | |
| return; | |
| } | |
| for (var handler in handlers) { | |
| handler(eventData); | |
| } | |
| } | |
| } |
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