Mixing MarshalByRefObject and Serializable

Question

Various sources explain that

When an object derives form MarshalByRefObject, an object reference will be passed from one application domain to anoth

Answer 1

I just did a quick test with List and it seems to work as I had hoped:

public class MBR : MarshalByRefObject
{
    List _list;
    public MBR() { _list = new List { this }; }
    public IList Test() { return _list; }
    public int X { get; set; }
}

// Later...
var mbr = AppDomainStarter.Start(@"C:\Program Files", "test", null, true);
var list = mbr.Test();
list[0].X = 42;
list.Clear();
Debug.WriteLine(string.Format("X={0}, Count={1}", mbr.X, mbr.Test().Count));

The output is X=42, Count=1, and the debugger shows that the List contains a __TransparentProxy. So clearly, the MarshalByRefObject is successfully marshaled by reference inside another object that was marshaled by value.

I would still like to see documentation or technical details if anyone can find some.

For anyone who is curious, I wrote this handy-dandy sandbox AppDomainStarter:

/// 
 starts an AppDomain.
public static class AppDomainStarter
{
    /// 
Creates a type in a new sandbox-friendly AppDomain.
    /// A trusted type derived MarshalByRefObject to create 
    /// in the new AppDomain. The constructor of this type must catch any 
    /// untrusted exceptions so that no untrusted exception can escape the new 
    /// AppDomain.
    /// Value to use for AppDomainSetup.ApplicationBase.
    /// The AppDomain will be able to use any assemblies in this folder.
    /// A friendly name for the AppDomain. MSDN
    /// does not state whether or not the name must be unique.
    /// Arguments to send to the constructor of T,
    /// or null to call the default constructor. Do not send arguments of 
    /// untrusted types this way.
    /// Whether the new AppDomain should run in 
    /// partial-trust mode.
    /// A remote proxy to an instance of type T. You can call methods 
    /// of T and the calls will be marshalled across the AppDomain boundary.
    public static T Start(string baseFolder, string appDomainName, 
        object[] constructorArgs, bool partialTrust)
        where T : MarshalByRefObject
    {
        // With help from http://msdn.microsoft.com/en-us/magazine/cc163701.aspx
        AppDomainSetup setup = new AppDomainSetup();
        setup.ApplicationBase = baseFolder;

        AppDomain newDomain;
        if (partialTrust) {
            var permSet = new PermissionSet(PermissionState.None);
            permSet.AddPermission(new SecurityPermission(SecurityPermissionFlag.Execution));
            permSet.AddPermission(new UIPermission(PermissionState.Unrestricted));
            newDomain = AppDomain.CreateDomain(appDomainName, null, setup, permSet);
        } else {
            newDomain = AppDomain.CreateDomain(appDomainName, null, setup);
        }
        return (T)Activator.CreateInstanceFrom(newDomain, 
            typeof(T).Assembly.ManifestModule.FullyQualifiedName, 
            typeof(T).FullName, false,
            0, null, constructorArgs, null, null).Unwrap();
    }
}