public T GetOrAddItem <T>(int id, Func <int, T> factory) where T : EntityBase
{
Type t = typeof(T);
CacheCollection collection;
if (!_collections.TryGetValue(t, out collection))
{
collection = _collections[t] = new CacheCollection <T>(factory);
}
CacheCollection <T> stronglyTyped = (CacheCollection <T>)collection;
return(stronglyTyped.Item(id));
}