从 INamedTypeSymbol.GetAttributes() 即 AttributeData 对象获取属性对象? [英] Get Attribute object from INamedTypeSymbol.GetAttributes() i.e. AttributeData object?

问题描述

我已经定义了以下属性

[AttributeUsage(AttributeTargets.Class)]
class DemoAttribute : Attribute
{
  public string SomeInfo { get; }

  public DemoAttribute(string someInfo)
  {
    this.SomeInfo = someInfo;
  }
}

可以应用于某些类，如下所示:

which can be applied to some class as follows:

[Demo("hello world")]
class Program { }

一个指向 Program 类的 INamedTypeSymbol 变量 namedTypeSymbol 提供给我，我设法获得了属性的名称.

An INamedTypeSymbol variable namedTypeSymbol pointing to the Program class is provided to me with which I managed to get the name of the attribute.

foreach(var attr in namedTypeSymbol.GetAttributes())
{
  if(attr.AttributeClass.Name == "DemoAttribute") { ... }
}

但是我如何访问设置为 SomeInfo 的内容?

But how do I access what was set as SomeInfo?

推荐答案

有两种方法可以将参数传递给属性.通过设置属性 ([Demo(SomeInfo="hello world")]) 或通过构造函数，正如您所做的那样.如果您使用命名方法，Ponas 将是正确的，解决方案在于 NamedArguments.

There are two ways you can pass arguments to attributes. Either by setting the property ([Demo(SomeInfo="hello world")]) or via the constructor, as you are doing. If you used the named approach, Ponas would be correct that the solution lies in NamedArguments.

但是，当您使用构造函数时，数据位于ConstructorArguments 中.这是一个TypedConstant的数组，从中可以得到值"hello world":

However, as you are using the constructor, the data is located in ConstructorArguments. This is an array of TypedConstant, from which you can get the value "hello world":

string attributeData = (string)attr.ConstructorArguments[0].Value;

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