Q:

Is it possible to serialize/deserialize immutable types with protobuf-net on Windows Phone 7/8?

Is it possible to serialize/deserialize types with protobuf-net on Windows Phone 7/8?
I've tried the code below, it seems Constructor skipping isn't supported (i.e. UseConstructor = false) so I created a parameterless constructor but the deserialization fails with "Attempt to access the method failed: Wp7Tests.ImmutablePoint.set_X(System.Double)"
public class ImmutablePoint
{
    public double X { get; private set; }
    public double Y { get; private set; }
    public ImmutablePoint() {}

    public ImmutablePoint(double x, double y)
    {
        X = x;
        Y = y;
    }
}
public sub Test()
{
        ImmutablePoint pt = new ImmutablePoint(1, 2);
        var model = TypeModel.Create();
        var ptType = model.Add(typeof(ImmutablePoint), false);
        ptType.AddField(1, "X");
        ptType.AddField(2, "Y");
        IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForApplication();

        using (var stream1 = new IsolatedStorageFileStream("test.bin", FileMode.Create, store))
        {
            try
            {
                model.Serialize(stream1, pt);
            }
            catch (Exception e)
            {                    
                Debugger.Break();
            }
        }
        const double EPSILON = 0.001;
        using (var stream1 = new IsolatedStorageFileStream("test.bin", FileMode.Open, store))
        {
            try
            {
                ImmutablePoint ptDeSer = (ImmutablePoint) model.Deserialize(stream1,null, typeof(ImmutablePoint));
                Debug.Assert(Math.Abs(pt.X - ptDeSer.X) < EPSILON);
                Debug.Assert(Math.Abs(pt.Y - ptDeSer.Y) < EPSILON);
            }
            catch (Exception e)
            {
                Debugger.Break();
            }
        }
}

A:

You can use a surrogate; here I'm decorating it with attributes, but it can be configured manually too:
[ProtoContract]
public class MutablePoint {
    [ProtoMember(1)] public double X { get; set; }
    [ProtoMember(2)] public double Y { get; set; }

    public static implicit operator MutablePoint(ImmutablePoint value) {
        return value == null ? null : new MutablePoint {X=value.X, Y=value.Y};
    }
    public static implicit operator ImmutablePoint(MutablePoint value) {
        return value == null ? null : new ImmutablePoint(value.X, value.Y);
    }
}

and then tell the model to use this whenever it sees ImmutablePoint:
var model = TypeModel.Create();
model.Add(typeof(MutablePoint), true);
model.Add(typeof(ImmutablePoint), false).SetSurrogate(typeof(MutablePoint));

The serializer will use the operators to switch between them as necessary. The serializer will use either implicit or explicit custom conversion operators.
EDIT:
Deserialize like this
ImmutablePoint ptDeSer = (ImmutablePoint)model.Deserialize(stream1, null, typeof(ImmutablePoint));

