自定义注释/ dart lang中的元数据 [英] custom annotation / Metadata in dart lang

问题描述

任何人可以在Dart中解释注释的使用吗？

Can any one explain me the use of annotations in Dart?

在文档中，我发现了这个例子：

In the documentations, I found this example:

library todo;

class todo {
  final String who;
  final String what;

  const todo(this.who, this.what);
}

后跟

import 'todo.dart';

@todo('seth', 'make this do something')
void doSomething() {
 print('do something');
}

所以，我应该在main（）中写什么来获取doSomething ）function executed？

so, what shall I write in the main() to get the doSomething() function executed?

感谢

推荐答案

>

Something like

import 'dart:mirrors';
import 'do_something.dart';
import 'todo.dart';


void main() {
  currentMirrorSystem().libraries.forEach((uri, lib) {
    //print('lib: ${uri}');
    lib.declarations.forEach((s, decl) {
      //print('decl: ${s}');
      decl.metadata.where((m) => m.reflectee is Todo).forEach((m) {
        var anno = m.reflectee as Todo;
        if(decl is MethodMirror) {
          print('Todo(${anno.who}, ${anno.what})');
          ((decl as MethodMirror).owner as LibraryMirror).invoke(s, []);
        };
      });
    });
  });
}

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