bloc_provider_new.dart

import 'package:flutter/material.dart';

typedef BlocBuilder<T> = T Function();
typedef BlocDisposer<T> = Function(T);

abstract class BlocBase {
  void dispose();
}

class BlocProvider<T extends BlocBase> extends StatefulWidget {
  const BlocProvider({
    super.key,
    required this.child,
    required this.blocBuilder,
    this.blocDispose,
  });

  final Widget child;
  final BlocBuilder<T> blocBuilder;
  final BlocDisposer<T>? blocDispose;

  @override
  _BlocProviderState<T> createState() => _BlocProviderState<T>();

  static T? of<T extends BlocBase>(BuildContext context) {
    final InheritedElement? inheritedElement = context.getElementForInheritedWidgetOfExactType<_BlocProviderInherited<T>>();
    if (inheritedElement == null) {
      return null;
    }

    final _BlocProviderInherited<T>? provider = inheritedElement.widget as _BlocProviderInherited<T>?;

    return provider?.bloc;
  }
}

class _BlocProviderState<T extends BlocBase> extends State<BlocProvider<T>> {
  late T bloc;

  @override
  void initState() {
    super.initState();
    bloc = widget.blocBuilder();
  }

  @override
  void dispose() {
    if (widget.blocDispose != null) {
      widget.blocDispose?.call(bloc);
    } else {
      bloc.dispose();
    }
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return _BlocProviderInherited<T>(
      bloc: bloc,
      child: widget.child,
    );
  }
}

class _BlocProviderInherited<T extends BlocBase> extends InheritedWidget {
  const _BlocProviderInherited({
    Key? key,
    required Widget child,
    required this.bloc,
  }) : super(key: key, child: child);

  final T bloc;

  @override
  bool updateShouldNotify(_BlocProviderInherited<T> oldWidget) => false;
}

First off, Love this code! It has made my life so easy! However, I ran into an issue where I was trying to use my bloc in a dialog, so was creating a custom builder in show dialog. I needed to make it a BlocProvider, since I was modifying the bloc in that dialog. So I just passed in my existing bloc. However, when I closed that dialog, it also got rid of my BlocProvider, and called the dispose() method, which closed the dispose method of my existing bloc. Which in turn closed all the streams on the bloc, and caused big issues.

I don't know the best way to do, but I added a parameter to the BlocProvider which determines if the bloc should be disposed. My changes are below. Just thought I'd pass along!

BlocProvider({
    Key key,
    @required this.child,
    @required this.bloc,
    this.disposeBloc: true,  /// Set to false if passing in an existing bloc.
  }): super(key: key);

  void dispose(){
    if (widget.disposeBloc) {
      widget.bloc?.dispose();
    }
    super.dispose();
  }

flutter/flutter#30325
我遇到一个问题