将动态方法调用移至类库会导致C＃中的RuntimeBinderException

Question

I was reading an interesting article using of DataFlow + dynamic method invocation to make an Actor model in C# . Here is the completed example verbatim.

using System;
using System.Threading.Tasks.Dataflow;

namespace ConsoleApplication
{
    public abstract class Message { }

    public abstract class Actor
    {
        private readonly ActionBlock<Message> _action;

        public Actor()
        {
            _action = new ActionBlock<Message>(message =>
            {
                dynamic self = this;
                dynamic mess = message;
                self.Handle(mess);
            });
        }

        public void Send(Message message)
        {
            _action.Post(message);
        }
    }

    class Program
    {
        public class Deposit : Message
        {
            public decimal Amount { get; set; }
        }

        public class QueryBalance : Message
        {
            public Actor Receiver { get; set; }
        }

        public class Balance : Message
        {
            public decimal Amount { get; set; }
        }

        public class AccountActor : Actor
        {
            private decimal _balance;

            public void Handle(Deposit message)
            {
                _balance += message.Amount;
            }

            public void Handle(QueryBalance message)
            {
                message.Receiver.Send(new Balance { Amount = _balance });
            }
        }

        public class OutputActor : Actor
        {
            public void Handle(Balance message)
            {
                Console.WriteLine("Balance is {0}", message.Amount);
            }
        }

        static void Main(string[] args)
        {
            var account = new AccountActor();
            var output = new OutputActor();

            account.Send(new Deposit { Amount = 50 });
            account.Send(new QueryBalance { Receiver = output });

            Console.WriteLine("Done!");
            Console.ReadLine();
        }
    }
}

This works as intended. Moving Actor & Message classes into a new class library and referencing properly causing an issue. When run it throws a RuntimeBinderException on the dynamic self.Handle(mess); within the Actor constructor saying Actors.Actor does not contain a definition for 'Handle' . Are there limitations to dynamic method calls I can't seem to find in the MSDN or syntax magic I missing to do this from a separate class library?

Answer 1

The original author got back to me.

Hi,

The problem is that you have declared your messages and actors inside the internal NotWorkingProgram class.

class NotWorkingProgram  // no access modifier! Default is 'internal' {
    public class Deposit : Message
    ...
    public class AccountActor : Actor
    {
        public void Handle(Deposit message)
        ...
    } } 

When you run the program the runtime tries to find a method named 'Handle' with a parameter of typ 'Deposit'. It can't find anything because the AccountActor class is not visible from the Actors Project. It is hidden inside the invisible NotWorkingProgram. If you make the NotWorkingProgram class public (or move the Deposit and AccountActor classes outside) it works!

Regards Johan

I'm leaving this here cause the RuntimeBinderException doesn't give much info, let alone any hint of class/method privacy being a possible root