The Dangers of Global Variables in Flutter

What are Global Variables?

Global variables are public variables that can be accessed from anywhere in your Flutter application. They’re often used as a quick fix to share data between widgets or screens. However, this convenience comes at a cost.

The Risks of Global Variables

Here are just a few reasons why you should avoid using global variables in Flutter:

• Complex Code Maintenance: When you use global variables, changing or removing one variable can have a ripple effect throughout your entire application. This makes it difficult to predict how changes will impact your code.
• Painful Unit Testing: Global variables make unit testing challenging because each test must reset the global state. This leads to fragile tests that are prone to breaking.
• Spaghetti Code: Global variables can be modified from anywhere in your application, making it hard to track changes and understand the flow of your code.
• Opposing Encapsulation: Global variables go against the principles of encapsulation, which is essential for writing clean, maintainable code.

Better Alternatives for State Management

So, what can you use instead of global variables? Here are some popular alternatives:

1. 1. Provider State Management Package: The Provider package allows you to manage state by wrapping your application in a provider widget. This approach simplifies state management and makes your code more predictable.

import 'package:provider/provider.dart';

void main() {
  runApp(
    MultiProvider(
      providers: [
        ChangeNotifierProvider(create: (_) => MyModel()),
      ],
      child: MyApp(),
    ),
  );
}

1. 1. GetX: GetX is a lightweight library that provides a simple way to manage state, navigate between screens, and inject dependencies.

import 'package:get/get.dart';

class MyController extends GetxController {
  final _count = 0.obs;

  void increment() => _count.value++;
}

1. 1. Riverpod: Riverpod is a state management library that helps you manage state in a unidirectional manner. It’s designed to make your code more predictable and easier to test.

import 'package:riverpod/riverpod.dart';

final counterProvider = Provider((ref) => 0);

void main() {
  runApp(
    ProviderScope(
      child: MyApp(),
    ),
  );
}

1. 1. Redux: Redux is a state management library that helps you manage state by providing a single source of truth for your application’s state.

import 'package:redux/redux.dart';

class MyApp extends StatelessWidget {
  final Store store;

  MyApp({required this.store});

  @override
  Widget build(BuildContext context) {
    return StoreProvider(
      store: store,
      child: MaterialApp(
        home: MyHomePage(),
      ),
    );
  }
}