Question

I created a following class within a namespace Global

namespace Global
{
    public static class Status
    {
        public static readonly char Active;
        public static readonly char Suspended;
        public static readonly char Terminiated;
        public static readonly char Deleted;

        private static readonly Dictionary<char, string> statusCollection;
        public static Dictionary<char, string> StatusCollection 
        { 
            get 
            { 
                return statusCollection; 
            }
        }

        static Status()
        {
            statusCollection = new Dictionary<char, string>();
            statusCollection.Add('A', "Active");
            statusCollection.Add('S', "Suspended");
            statusCollection.Add('T', "Terminated");
            statusCollection.Add('D', "Deleted");

            Active = 'A';
            Suspended = 'S';
            Terminiated = 'T';
            Deleted = 'D';
        }
    }

    public class a
    {
        public void add()
        {
            //How to make this collection readonly
            Status.StatusCollection.Add('N', "asd"); 

            Status.Active = 'M'; //Throws a compile time exception, changes not allowed
        }
    }
}

Strange behaviour When I tried updating Status.Active in immediate window, I was expecting that value won’t change but changes were allowed. Does that mean we can change value of readonly variable via reflection or runtime ?

Answer 1

Yes, you can change the value of a readonly property at runtime through Reflection. And here’s a very simple POC:

public class Program
{
    private static readonly string Foo = "Bar";

    static void Main()
    {
        typeof(Program)
            .GetField("Foo", BindingFlags.Static | BindingFlags.NonPublic)
            .SetValue(null, "new value");
        Console.WriteLine(Foo);
    }
}

When you run this console application it will print:

new value