Hi.

I am currently creating a custom property which will hold a list of banners. The banners are an imagevault media instance and a link which corresponds. I am following the tutorial made by Joel Abrahamsson, http://joelabrahamsson.com/creating-a-custom-episerver-property-with-a-custom-class-as-value/ even though it is a bit old I think I have managed to get everything right. The problem I am facing is when implementing IReadOnly's (EPiServer.Data.Entity) method CreateWritableClone(). The error message says that the return type should be of 'object' and when I change to object it says the return type should be 'BannerList'. I have supplied my custom class BannerList.cs below.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Collections;
using EPiServer.Data.Entity;

namespace EPiServer.Templates.InGellivare.BIT
{
    public  class BannerList : IEnumerable<Banner>, IReadOnly<BannerList>
    {
        private List<Banner> values;
        private bool isReadOnly;
        private bool isModified;

        #region Collection related

        public BannerList()
        {
            values = new List<Banner>();
        }

        public IEnumerator<Banner> GetEnumerator()
        {
            return (IEnumerator<Banner>)values.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }

        public void Add(Banner banner)
        {
            ThrowIfReadOnly();

            isModified = true;

            values.Add(banner);
        }

        #endregion

        #region Object related (Create, Copy, Comparison et cetera)

        public BannerList CreateWritableClone()
        {
            var copy = new BannerList();
            copy.values = new List<Banner>(values);
            copy.isReadOnly = false;

            return (BannerList)copy;
        }

        public BannerList Copy()
        {
            var copy = (BannerList)MemberwiseClone();

            copy.values = new List<Banner>(values);

            return copy;
        }

        public override bool Equals(object obj)
        {
            var compareTo = obj as BannerList;

            if (compareTo == null)
            {
                return false;
            }

            return values.SequenceEqual(compareTo.values);
        }

        public override string ToString()
        {
            return JsonHelper.JsonSerializer<List<Banner>>(values);
        }

        public static BannerList Parse(string value)
        {
            if (value == null)
            {
                throw new ArgumentException("Cannot parse Bannerlist objects from null", "value");
            }

            var result = new BannerList();
            var banners = JsonHelper.JsonDeserialize<List<Banner>>(value);
            result.values.AddRange(banners);
            return result;
        }

        #endregion

        #region Version & Access control

        public void MakeReadOnly()
        {
            isReadOnly = true;
        }

        public bool IsReadOnly
        {
            get { return isReadOnly; }
        }

        private void ThrowIfReadOnly()
        {
            if (IsReadOnly)
            {
                throw new NotSupportedException("The list of banners is read-only.");
            }
        }

        public bool IsModified
        {
            get
            {
                return isModified;
            }
            set
            {
                ThrowIfReadOnly();
                isModified = value;
            }
        }

        #endregion
    }
}

And the error message reads as following:

Error 1 'EPiServer.Templates.InGellivare.BIT.BannerList' does not implement interface member 'EPiServer.Data.Entity.IReadOnly.CreateWritableClone()'. 'EPiServer.Templates.InGellivare.BIT.BannerList.CreateWritableClone()' cannot implement 'EPiServer.Data.Entity.IReadOnly.CreateWritableClone()' because it does not have the matching return type of 'object'. C:\EPiServer\Sites\GVE\Templates\InGellivare\BIT\BannerList.cs 10 19 nyaGellivare

Thanks in advance,

David Rutqvist