using System;

using System.Collections.Generic;

using System.Collections.ObjectModel;

​

public class Program

{

    public static void Main()

    {   

        var foo = ProperDictMapping.Mapping[1];

        var bar = ProperDictMapping.Mapping[1]; 

        Console.WriteLine("Proper");

        Console.WriteLine("");

        Console.WriteLine($"{foo}\r\n{bar}");

        foo = ShittyDictMapping.Mapping[1];

        bar = ShittyDictMapping.Mapping[1];

        Console.WriteLine("");

        Console.WriteLine("Shitty");

        Console.WriteLine("");

        Console.WriteLine($"{foo}\r\n{bar}");

        foo = ReadonlyShittyDictMapping.Mapping[1];

        bar = ReadonlyShittyDictMapping.Mapping[1];

        Console.WriteLine("");

        Console.WriteLine("ReadonlyShitty");

        Console.WriteLine("");

        Console.WriteLine($"{foo}\r\n{bar}");

        foo = ReadonlyShittyDictMapping.Mapping[1];

        ReadonlyShittyDictMapping.Mapping[1] = Guid.NewGuid();

        bar = ReadonlyShittyDictMapping.Mapping[1];

        Console.WriteLine("");

        Console.WriteLine("ReadonlyShitty");

        Console.WriteLine("");

        Console.WriteLine($"{foo}\r\n{bar}");

    }

​

    public static class ProperDictMapping

    {

        public static ReadOnlyDictionary<int, Guid> Mapping { get; } = new ReadOnlyDictionary<int, Guid>(new Dictionary<int, Guid>

        {

            { 1 , Guid.NewGuid() }

        });

    }

    public static class ReadonlyShittyDictMapping

    {

        public static readonly Dictionary<int, Guid> Mapping = new Dictionary<int, Guid>

        {

            { 1 , Guid.NewGuid() }

        };

    }

    public static class ShittyDictMapping

    {

        public static Dictionary<int, Guid> Mapping => new Dictionary<int, Guid>

        {

            { 1 , Guid.NewGuid() }

        };

    }

}

​