Auto-Registering Types

AutofacMvc.cs

using System;
using System.Linq;
using System.Reflection;
using System.Web.Mvc;
using Autofac;
using Autofac.Builder;
using Autofac.Integration.Mvc;
using Web.Registration;

[assembly: WebActivator.PreApplicationStartMethod(typeof(Web.App_Start.AutofacMvc), "Start")]

namespace Web.App_Start
{
    public static class AutofacMvc
    {
        public static void Start()
        {
            var builder = new ContainerBuilder();
            builder.RegisterControllers(typeof(MvcApplication).Assembly);

            builder.RegisterAssemblyModules();

            builder.RegisterAutos();

            var container = builder.Build();
            DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
        }

        private static void RegisterAutos(this ContainerBuilder builder)
        {
            var registered = AppDomain.CurrentDomain
                .GetAssemblies()
                .SelectMany(a => a.GetTypes())
                .Where(t => t.GetCustomAttributes().Any(a => a.GetType() == typeof (AutoRegisterAttribute)));

            foreach (var type in registered)
            {
                var attribute = type.GetCustomAttribute<AutoRegisterAttribute>();
                builder.RegisterType(type).WithScope(attribute.Scope).AsImplementedInterfaces();
            }
        }

        private static IRegistrationBuilder<object, ConcreteReflectionActivatorData, SingleRegistrationStyle> WithScope(this IRegistrationBuilder<object, ConcreteReflectionActivatorData, SingleRegistrationStyle> builder, Scope scope)
        {
            switch (scope)
            {
                case Scope.Singleton:
                    return builder.SingleInstance();
                case Scope.Request:
                    return builder.InstancePerHttpRequest();
            }
            return builder;
        }
    }
}

AutoRegisterAttribute.cs

using System;

namespace Web.Registration
{
    public class AutoRegisterAttribute : Attribute
    {
        public Scope Scope { get; set; }

        public AutoRegisterAttribute()
        {
            Scope = Scope.Dependecy;
        }
    }

    public enum Scope
    {
        Dependecy,
        Request,
        Singleton
    }
}