ProtoBuf-net serializing IEnumerable

Question

I'm trying to use ProtoBuf-NET in my project (it's mostly Silverlight 4 project).

I'm having difficulties serializing my Model collections, they all are defined like this:

private List<T> _itemsSet;
public IEnumerable<T> TSet
{
    get {return _itemsSet;}
    set {_itemsSet = value == null ? new List<T>() : new List<T>(value);}
}
public void AddT(T item)
{
    //Do my logic here
    _itemsSet.Add(item);
}

Update: First I can't serialize it - No serializer defined for type: System.Collections.Generic.IEnumerable1[MyType]`. Second I think I will be unable to desirialize it based on manual, and protobuf-net source code analyzes.

1. Is there a way to extend protobuf-net to supply delegate to external Add method in ProtoMemeber attribute?
2. Why using ProtoMember(1, OverwriteList=true) doesn't work? Doesn't it suppose to overwrite collection and shouldn't care about Add<T>() method? Why it just don't try to set this property to T[] or List<T> or any set assignable to IEnumerable<T> ?
3. Is there a way to supply custom reflection mechanism to work with private fields in Silverlight, like: implementing: public interface IReflectable{ object GetValue(FieldInfo field); void SetValue(FieldInfo field, object value); } to work with private fields. I have used such approach to work with private fields with Db4o: http://community.versant.com/Forums/tabid/98/aft/10881/Default.aspx
4. What options I have except creating inherited MyTypeCollection<T> : Collection<T> ?

Answer 1

1. not at current, no; the type exposed must have (at a minimum) an Add method. While I have no objection to investigating the possibility of an Add outside the object itself, this is complicated since you are then looking at a different "primary" object (the sequence vs the container). However; if your parent object implemented IEnumerable<T> (returning _itemsSet.GetEnumerator() etc), then it would find the Add automatically

2. I can't see the context here; however, I suspect that without the Add it still isn't happy to consider it a list in the first place. I see the way you are going with that, though, and it is perhaps a way it could reason "I can use a List<T> here)

3. It isn't something I've investigated, to be honest; so: no

4. The type exposed in the property must, as a minimum: implement IEnumerable (although IEnumerable<T> would be preferred), and expose an Add(T) method. It doesn't have to be Collection<T> / List<T> / etc - simply: it must (at present) have some mechanism to add. IList<T> would be a a pragmatic option, but I gather that isn't quite what you want.

Jonathan is right that a surrogate for the outer-class (the thing which has _itemsSet, TSet and AddT) might also be an option.

If the outer-class only exists to have the collection and the add method, then just adding : IEnumerable<T> and renaming AddT to Add would probably make it work.

Answer 2

I was trying to cut corners, and to reuse my model as a message contract, but this is actually wrong aproach. The way to go is to create DTO's specialized classes and converter to you model, anyway it's good to separate your model from messages.

I must criticize Marc though, for adding ProtoContract and ProtoMemeber attributes that lure users to reuse their model by attributing it.