using System;

using System.Reflection;

​

[FieldTag("Base")]

public abstract class FieldBase {

    public string FieldTag {

        get {

            FieldTagAttribute fieldTagAttribute = (FieldTagAttribute) (

                GetType().GetCustomAttribute(typeof(FieldTagAttribute), inherit: false)

            );

            if (fieldTagAttribute == null) {

                throw new InvalidOperationException(String.Format("Class {0} has no attribute [FieldTag]. Please add the attribute to this class.", GetType()));

            }

            return fieldTagAttribute.FieldTag;

        }

    }

}

​

[System.AttributeUsageAttribute(System.AttributeTargets.Class, Inherited = false)]

public class FieldTagAttribute : Attribute {

   public FieldTagAttribute(string fieldTag) {

       FieldTag = fieldTag;

   }

​

   public string FieldTag { get; set; }

}

​

[FieldTag("32A")]

public class Field32A : FieldBase {

    public string Value{ get; set; }

    public override string ToString() {

        return ":" + FieldTag + ":" + Value;

    }

}

​

public class Program {

    public static void Main() {

        Field32A field32A = new Field32A { Value = "12345" };

        field32A.ToString().Dump();

    }

}

​