在没有状态管理工具的情况下在 flutter 中传递状态

发布于 01-12 16:25 字数 1571 浏览 2 评论 0原文

我正在 Udemy 上学习 Flutter 课程:使用 Dart 完成 Flutter 应用程序开发训练营 我正在阅读提供程序包章节。作为状态管理的介绍,我们使用以下示例代码来说明在不使用状态管理工具的情况下在类和小部件之间传递状态是多么耗费精力。代码如下:

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  final String data = 'this is the test data';
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
          appBar: AppBar(
            title: MyText(),
          ),
          body: Level1(data),
        ),
      );
  }
}

class Level1 extends StatelessWidget {
  final String data;
  Level1(this.data);

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Level2(data),
    );
  }
}

class Level2 extends StatelessWidget {
  final String data;
  Level2(this.data);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        MyTextField(),
        Level3(data),
      ],
    );
  }
}

class Level3 extends StatelessWidget {
  final String datta;

  Level3(this.datta);

  @override
  Widget build(BuildContext context) {
    return Container(
        child: Text('data')
    );
  }
}

导师在这里想表达的观点是:

“在没有状态管理工具的情况下,如果我们想要MyApp类中提到的第一个变量data要在 Level3 课程中使用,我们需要钻取所有其他课程:Level1Level2

我不确定她为什么不这样做” t 立即调用 Level3 构造函数MyApp 类?为什么在这里可以选择钻研课程?我知道这对于编码来说不是最佳的,我同意,但我们可以直接调用 Level3 构造函数!我们不能吗?有人可以提供更多解释吗?

I am going through a flutter course on Udemy: Complete Flutter App Development Bootcamp with Dart I am in the provider package chapter. as an intro to state management, we have the following example code to illustrate how effort consuming it is to pass state in between classes and widgets without the use of a state management tool. the code is as follows:

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  final String data = 'this is the test data';
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
          appBar: AppBar(
            title: MyText(),
          ),
          body: Level1(data),
        ),
      );
  }
}

class Level1 extends StatelessWidget {
  final String data;
  Level1(this.data);

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Level2(data),
    );
  }
}

class Level2 extends StatelessWidget {
  final String data;
  Level2(this.data);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        MyTextField(),
        Level3(data),
      ],
    );
  }
}

class Level3 extends StatelessWidget {
  final String datta;

  Level3(this.datta);

  @override
  Widget build(BuildContext context) {
    return Container(
        child: Text('data')
    );
  }
}

The point that the tutor is trying to make here is:

"with no state management tools, if we want the first variable data mentioned in MyApp class to be used also in Level3 class we will need to drill through all other classes : Level1 and Level2"

I am not sure why she isn't calling the Level3 constructor immediately in MyApp class? why is this drilling through classes even an option here? I understand that it is not optimal for coding and I agree, but we can just call Level3 constructor directly! can't we? can someone provide more explanation?

如果你对这篇内容有疑问,欢迎到本站社区发帖提问 参与讨论,获取更多帮助,或者扫码二维码加入 Web 技术交流群。

扫码二维码加入Web技术交流群

发布评论

需要 登录 才能够评论, 你可以免费 注册 一个本站的账号。

评论(1

横笛休吹塞上声2025-01-19 16:25:19

嗯,这是在 Flutter 中教授状态管理的糟糕方法!

Flutter 的内置状态管理已经很棒了。您需要的是查看 InheritedModel,它允许您沿着小部件链一路继承状态,甚至可以选择您想要继承的状态的某个方面。

以下视频介绍了如何在 Flutter 中使用 InheritedModelhttps://www.youtube.com/watch?v=0vl35jtpsfs&list=PL6yRaaP0WPkUf-ff1OX99DVSL1cynLHxO&index=4&ab_channel=VandadNahavandipoor

Well that's a bad way of teaching state management in Flutter!

Flutter's built-in state management is great already. What you need is to look at the InheritedModel that allows you to inherit state all the way down the widget chain and to even pick an aspect of the state that you want to inherit.

Here is a video that explains how you can use InheritedModel in Flutter: https://www.youtube.com/watch?v=0vl35jtpsfs&list=PL6yRaaP0WPkUf-ff1OX99DVSL1cynLHxO&index=4&ab_channel=VandadNahavandipoor

~没有更多了~
我们使用 Cookies 和其他技术来定制您的体验包括您的登录状态等。通过阅读我们的 隐私政策 了解更多相关信息。 单击 接受 或继续使用网站,即表示您同意使用 Cookies 和您的相关数据。
原文