这是为什么合法的吗？指的是恒定的类型，从属性*月*的类型，而不与类型名称prefixing？ [英] Why is this legal? Referring to a constant in a type, from an attribute *on* the type, without prefixing with type name?

问题描述

请看下面 LINQPad 计划：

void Main() { }

[TestAttribute(Name)]
public class Test
{
    public const string Name = "Test";
}

[AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = false)]
[Serializable]
public class TestAttribute : Attribute
{
    public TestAttribute(string dummy)
    {
    }
}

这编译顺利。为什么呢？

This compiles without a hitch. Why?

具体做法是：

[TestAttribute(Name)]
public class Test
{
    public const string Name = "Test";

我为什么不都这样写：

Why don't I have to write this:

               vvvvv
[TestAttribute(Test.Name)]
public class Test
{
    public const string Name = "Test";

被认为是内部的类型，因而在范围属性声明？

Is the attribute declaration deemed to be "inside" the type, and thus in scope?

推荐答案

的属性实例声明的范围确实是在其上附着，或类型的（在一个方法，参数等的情况下）含有在其上附着的元件的类型。

The scope of an attribute instance declaration is indeed that of the type on which it is attached, or (in the case of a method, parameter, etc.) the type containing the element on which it is attached.

我找不到具体的上的东西，虽然标准的确说：

I can't find anything specific on that, though the standard does say:

属性可以在全局范围指定（指定的装配包含属性）和类型声明（§16.6），类成员声明（§17.1.4），结构成员声明（第18.2节） ，接口成员声明（§20.2），枚举成员声明（§21.1），访问器声明（§17.6.2），事件访问器声明（§17.7），形式参数数组中的元素（§ 17.5.1），和类型参数数组中的元素（§25.1.1）。

Attributes can be specified at global scope (to specify attributes on the containing assembly) and for type-declarations (§16.6), class-member-declarations (§17.1.4), struct-member-declarations (§18.2), interface-member-declarations (§20.2), enum-member-declarations (§21.1), accessor-declarations (§17.6.2), event-accessor-declarations (§17.7), elements of formal-parameter-lists (§17.5.1), and elements of type-parameter-lists (§25.1.1).

虽然它没有明确说的类范围内任何东西，它不区分在全球范围内全局属性的范围较广。

While it doesn't explicitly say anything about class scope, it does differentiate that from the wider scope of global attributes in "global scope".

我注意到，您的类CIL是：

I'd note that the CIL of your class would be:

class public auto ansi beforefieldinit SomeNamespace.Test extends [mscorlib]System.Object
{
  .custom instance void SomeNamespace.TestAttribute::.ctor(string) = (
    01 00 04 54 65 73 74 00 00
  )
  .field public static literal string Name = "Test"
  .method public hidebysig specialname rtspecialname instance void .ctor () cil managed
  {
    .maxstack 8
    ldarg.0
    call instance void [mscorlib]System.Object::.ctor()
    ret
  }
}

在CIL作用域比C＃

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