reflection - .NET 世界中的 "mark a field as literal"是什么意思？

Question

根据微软的文档，FieldInfo.GetValue(object)会抛出 NotSupportedException如果:

"A field is marked literal, but the field does not have one of the accepted literal types."

我不知道这意味着什么

"mark a field as literal."

我想了解这一点，以便我知道如何防范这种异常。

Answer 1

一个 literal是 const field 。每个 const 字段的值都在编译时通过从文字初始化来确定。看看这个代码

using System;
using System.Reflection;


public class Program
{
    const int literal_int = 5;
    readonly int literal_int_two = 5;
    const string literal_string = "Fun";
    const Random literal_random = null;
    int non_literal;

    public static void Main()
    {
        foreach (FieldInfo f in typeof(Program).GetFields(BindingFlags.Instance 
        | BindingFlags.NonPublic
        | BindingFlags.Static
        | BindingFlags.FlattenHierarchy))
        {
            Console.WriteLine("{0} is literal - {1}", f.Name, f.IsLiteral);
            try
            {
                Console.WriteLine("GetValue = {0}", f.GetValue(null));
            }
            catch{}
        }
    }
}

输出:

literal_int is literal - True
GetValue = 5
literal_int_two is literal - False
literal_string is literal - True
GetValue = Fun
literal_random is literal - True
GetValue = 
non_literal is literal - False

然而，

but the field does not have one of the accepted literal types

可以接受解释，我找不到一个没有“一种可接受的文字类型”的文字示例(无论这意味着什么)。

通过简要查看 source code ，我找不到一个相关的代码来代表这个异常。您应该安全地忽略此条款。