using System;

​

public class MyClass

{

    /* Flag Enum - Access via FilePerms */

    [Flags] enum Flag_FilePerms : int

    {

        None = 0,

        Create = 1,

        Read = 2,

        Update = 4,

        Delete = 8

    }

​

    /* FlagEnum base class */

    abstract class FlagEnum

    {

        protected string __alias__;

        protected Type __etype__;

        protected Type __utype__;

​

        public FlagEnum(string sAlias, Type etype)

        {

            if (!etype.IsEnum)

                throw new Exception($"etype is not an Enum Type. Got: {etype.Name}");

            this.__alias__ = sAlias;

            this.__etype__ = etype;

            this.__utype__ = Enum.GetUnderlyingType(etype);

            // Do validation here. 

            // Eg. ensuring that sequence follows power of 2 with None = 0 as first entry ...

            //     Note: .net does not validate this automatically with the Flags() 

        }

        // implement custom methods...

    }

​

​

    /* Enum wrapper */

    class Flag_FilePerms_Wrapper : FlagEnum 

    {

        public Flag_FilePerms None     = Flag_FilePerms.None;

        public Flag_FilePerms Create   = Flag_FilePerms.Create;

        public Flag_FilePerms Read     = Flag_FilePerms.Read;

        public Flag_FilePerms Update   = Flag_FilePerms.Update;

        public Flag_FilePerms Delete   = Flag_FilePerms.Delete;

        public Flag_FilePerms_Wrapper(string sAlias) : base(sAlias, typeof(Flag_FilePerms))

        {

        }

    }

    private static void pc(object o){Console.Write($"{o}\n");}

​

    /* singleton for use in business logic */

    static Flag_FilePerms_Wrapper FilePerms = new Flag_FilePerms_Wrapper("FilePerms");

​

​

    static void Main(string[] args)

    {

        /* business logic */

        var perms = FilePerms.Update | FilePerms.Create;

​

        pc($"perms.HasFlag(FilePerms.Create): {perms.HasFlag(FilePerms.Create)}"); /* True */

        pc($"perms.HasFlag(FilePerms.Delete): {perms.HasFlag(FilePerms.Delete)}"); /* False */

​

        var perms_none = FilePerms.None;

​

        pc($"perms_none == FilePerms.None: {perms_none == FilePerms.None}"); /* True */

        pc($"perms == FilePerms.None: {perms == FilePerms.None}"); /* False */

    }

​

}