Welcome to the future of Flutter development! 想象一下这样一个世界:编写样板代码的乏味任务已经成为过去. 向…问好 飞镖宏 – your new secret weapon for supercharging productivity. 这些强大的运行时代码生成工具在幕后发挥着它们的魔力, 无缝地减少了样板文件，消除了对繁琐的辅助工具的需求. With Flutter 宏, you can focus on crafting beautiful, high-performance apps while the 宏 h和le the repetitive tasks, 使您的开发过程比以往任何时候都更快、更有效. 准备解锁一个新的水平的编码自由和效率与Flutter宏!
那么,什么 是 宏?
Dart宏是一个可自定义的代码片段，它接受其他代码作为输入，并对其进行处理 实时 to create, modify, or add new elements. 宏提供了一种可重用的方式来处理重复的任务和模式, 特别是在处理需要迭代类的字段时. Right now t在这里’s one 宏 ready to go: JsonEncodable. As the name suggests, JsonEncodable generates the tedious fromJson 和 toJson methods for you.
Macros don’t require anything extra to run, 只需向代码中添加所需的适当注释，并在实时生成样板代码时进行观察! With them, code is 不 written to the disk, so say goodbye to the 部分 keyword. Macros directly 增加 the existing class.
What problem 是 they solving
宏，作为 static metaprogramming 工具，提供运行时代码生成解决方案的替代方案(例如 build_runner, json_serializable). Macros eliminate the need for a secondary tool, being integrated into Dart language, 通过Dart工具在后台自动执行您键盘上的每一个按键
- No extra steps: Macros build your code in 实时 as you write.
- No performance hit: All the code generation happens directly in the compiler.
- Clean 和 organised: No extra files cluttering up your project.
- Clear error messages: 自定义诊断出现在您的IDE中，就像常规编译器消息一样.
例子
Let’s comp是 3 different code snippets, first without any code gen, second with 冻结 和 then third with 宏
No Code Generation
图片标题
对于这样一个通用的样板来说，仅仅是将这部分输入出来所花费的时间就比应该花费的时间长得多. Obviously this is 不 even the whole class, it’s still missing the hashCode, == operator 和 possibly the toString 覆盖, 和 then do this for every (or at least most) model classes, 结果是你花了很多时间在很容易出错的样板代码上.
Now let’s look at 冻结
这看起来比手工编写函数更不容易出错, but now you’ve got 2 new files that you need to work around, push to the project github or set up .gitignore. A lot less work than with manual writing, 但是这些文件中仍然有一些部分可以被视为样板文件.
Now let’s check it with 宏
就是这样! No other code needed to make this work. 在键入最后一个分号时，代码已经生成并准备使用. 写完这个类后，我们可以转到其他文件，并能够做这样的事情:
宏帮助您专注于重要的内容(产品的核心逻辑)，并将您从耗时的工作中解放出来, boring tasks that 是 essential but often get in the way.
It’s experimental - how to try it out
Set up the environment:
- Switch to the Dart dev channel or flutter master channel
- Run 飞镖 –version to make sure you have Dart version `3.5.0-152` or later
- 编辑pubspec中的SDK约束以要求Dart版本:SDK: ^3.5.0-152.
- Add the package json to dependencies: 飞镖 pub add json.
- Enable the experiment in your package's analysis_options.yaml文件. file at the root of your project:
- Import the package to the file that you’re planning to use
import 'package:json/json.飞镖”;
- Run the project with the experimental flag
飞镖 run --enable-experiment=宏 bin/my_app.飞镖
Example of how to create custom 宏
Your first custom 宏 should have two key segments, the 宏 关键字和一个接口，该接口确定为哪个接口确定宏. You can find the list of existing interfaces 在这里.
例如, a 宏 that is applicable to enums, 和 adds new declarations to the enum, would implement the EnumDefinitionMacro interface:
创建了自定义宏后，可以将其添加到声明中，如下所示:
要记住的重要事情是，在高级别的宏使用构建器方法来组合声明的属性 标识符 on those properties, gat在这里d through introspection of the codebase
Stable release timeline
在撰写本文时，还不知道将宏发布到stable中. 具体的日期还没有确定，因为宏是通过深度自省应用它们的代码库来工作的. jsonencoable宏发布的总体目标预计将在2024年底之前发布, 和 the stable release of the full functionality, including creating custom 宏, for early-to-mid 2025.
常见问题解答
What is 增加ation in 飞镖?
通过“增强”关键字的增强是下一步的进化 部分 关键字和部件文件，只是没有额外的语法，使您的类不那么干净. 增强允许在主类文件之外定义类函数.
例如 we have this main class 人:
Now with the base class set, 我们可以在项目的不同部分创建自己的json序列化方法, 是这样的:
And after adding the import below, you will be good to go!
Why migrate from build_runner/freezed to 宏?
To improve the developer experience, of course! T在这里 is 不hing wrong with these packages, they do the job perfectly, but with 宏 we make code cleaner by removing the _$ syntax needed for the packages mentioned above, 同时也减少了开发人员管理被忽略的文件的工作量，或者在同行评审中无休止地滚动生成的文件，以获得拉取请求的关键.
