pattern.dart

import 'package:flutter/material.dart';

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

void main() {
  runApp(EmailApp());
}

class EmailApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    PersonManager personManager = Overseer().fetch(PersonManager);

    return MaterialApp(
        home: Scaffold(
      appBar: AppBar(title: Text("my app"), centerTitle: true),
          
              body:   Center (child:ListView(
                  
                  
                  children :   personManager.fetchNames().map((name)=>Text(name)).toList()
                  
                  
                  
                  
                  ))
    ));
  }
}

class PersonManager {
  List<String> names = ["Walaa", "Zikra"];

  List<String> fetchNames() => names;
}

class Overseer {
  Map<dynamic, dynamic> repository = {};

  Overseer() {
    register(PersonManager, PersonManager());
  }
  register(name, object) {
    repository[name] = object;
  }

  fetch(name) => repository[name];
}