如何检索标有元数据的功能 [英] How retrieve function that marks with metadata

问题描述

查看以下代码段。

import "dart:mirrors";

class meta {
    final String data;

    const meta(this.data);
}


@meta("Tag")
doSomething() => print("You have to do something");

void main() {
    doSomething();
}

如何获取函数，即带有元数据标签的市场？在我的示例中，我想找出哪种方法带有meta标签。

How can I retrieve functions, that is market with metadata tags? In my example, I want to find out, which method is marked with meta tags.

推荐答案

您可以执行以下操作：

you could do something like this:

void main() {
    doSomething();
    getMetaData();
}

void getMetaData() {
  LibraryMirror currentLib = currentMirrorSystem().libraries.values.last;
  currentLib.declarations.forEach((Symbol s, DeclarationMirror mirror) {
    if(mirror.metadata.length > 0) {
      print('Symbol $s has MetaData: "${mirror.metadata.first.reflectee.data}"');
    }
  });
}

这应该给您：

You have to do something
Symbol Symbol("doSomething") has MetaData: "Tag"

您还可以分析另一个项目中的文件，并对该文件使用dart：mirrors，而不用检查当前的库。也许 libraries.values.last 不会总是返回当前库-因此您可能需要更改它。就我而言，它行得通。

You could also analyze your files from another project and use dart:mirrors on that file instead of inspecting the current library. Maybe libraries.values.last will not always return the current library - so you might need to change it. In my case it worked.

这篇关于如何检索标有元数据的功能的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！