C# caching object

RepoCache.cs

using System;
using System.Runtime.Caching;

namespace Application.Caching
{
    public static class RepoCache
    {
        static ObjectCache cache = MemoryCache.Default;

        public static bool UseCache
        {
            get
            {
            #if (DEBUG)
                return false;
            #else
                return true;
            #endif
            }
        }

        public static T Retrieve<T>(string methodName, Func<T> fetchData, params object[] arguments) where T : class
        {
            var cacheKey = GenerateCacheKey(methodName, arguments);
            var result = cache[cacheKey] as T;

            if(result != null)
                return result;

            return Add<T>(fetchData(), cacheKey);
        }

        private static T Add<T>(T item, string cacheKey) where T : class
        {
            if (UseCache && item != null)
            {
                var i = item as System.Collections.ICollection;
                if (i != null)        //if this is a collection type
                {
                    if (i.Count == 0) //don't cache empty collections
                        return item;
                }
                cache.Set(cacheKey, item, null, null);
            }

            return item;
        }

        private static string GenerateCacheKey(string methodName, params object[] arguments)
        {
            if (arguments == null || arguments.Length == 0)
                return methodName;

            return string.Format("{0}~{1}", methodName, String.Join("~", arguments));
        }
    }
}

/*  EXAMPLE:
        public User GetUser(int id)
        {
            return RepoCache.Retrieve<User>("GetUser", () =>
            {
                using (var context = new DNSEntities())
                {
                    return (from c in context.Users select c where c.id=id).FirstOrDefault();
                }
            }, id);
        }
*/