Return a Stream that emits null and done event when didChangeDependencies is called for the first time

did_change_dependencies

return a stream that emits null and done event when didchangedependencies is called for the first time.

author: petrus nguyễn thái học

import 'dart:async';

import 'package:did_change_dependencies/did_change_dependencies.dart';
import 'package:flutter/material.dart';
import 'package:rxdart_ext/rxdart_ext.dart';

class bloc {
  stream<string> message$ = stream.empty(); // just demo
}

class mypage extends statefulwidget {
  const mypage({key? key}) : super(key: key);

  @override
  _mypagestate createstate() => _mypagestate();
}

class _mypagestate extends state<mypage> with didchangedependenciesstream {
  final bloc = bloc();
  final subscriptions = <streamsubscription<void>>[];

  @override
  void initstate() {
    super.initstate();

    final handle = (string msg) {
      // safe to access scaffoldmessengerstate.
      scaffoldmessenger.of(context).showsnackbar(
        snackbar(content: text(msg)),
      );
    };
    subscriptions <<
        didchangedependencies$
            .exhaustmap((value) => bloc.message$)
            .listen(handle);

    subscriptions <<
        didchangedependencies$.listen((event) {
          // do something when `didchangedependencies` is called for the first time.
        });
  }

  @override
  void dispose() {
    super.dispose();
    subscriptions.foreach((s) => s.cancel());
  }

  @override
  widget build(buildcontext context) {
    return container();
  }
}

extension _listext<t> on list<t> {
  void operator <<(t t) => add(t);
}