Expression Redux

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Linq.Expressions;
using System.Net.Http;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace ConsoleApplication5
{
    interface IConsume<TMessage>
    {
        void Consume(TMessage message);
    }

    class Consumer : IConsume<int>
    {
        public void Consume(int message)
        {
            Console.WriteLine("Here's " + message);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var c = new Consumer();

            var consume = CreateConsumerDelegate<int>(c);

            consume(c, 1);
        }

        private static Action<object, object> CreateConsumerDelegate<TMessage>(object consumer)
        {
            // Action<object, object> consume = (instance, arg) => ((Type)instance).Consume((TMessage)arg)

            var instance = Expression.Parameter(typeof(object));
            var arg = Expression.Parameter(typeof(object));

            var method = consumer.GetType().GetMethod("Consume");
            var convertedInstance = Expression.Convert(arg, consumer.GetType());
            var convertedArg = Expression.Convert(instance, typeof(TMessage));

            var call = Expression.Call(convertedInstance, method, convertedArg);
            var func = Expression.Lambda<Action<object, object>>(call, arg, instance);
            return func.Compile();
        }
    }
}