Question

I have two objects that should be registered together, and also share the same lifetime scoping. I would like to provide a registration extension to encapsulate this and retain the registration fluency, but I need some help. Here’s the situation I’m in:

public static IRegistrationBuilder<?, ?, ?> 
  RegisterChannel<T>(this ContainerBuilder builder, Func<IComponentContext, ChannelFactory<T>> @delegate)
{
  // channelfactory and sharedchannel should have same lifetime configuration
  var channelfactoryreg = builder.Register(c => @delegate(c));
  var sharereg = builder.RegisterType<Wcf.SharedChannel<T>>();

  // is it possible to combine them and return?
  return ???;
}

How do I fill in the blanks so that I can write (e.g.) builder.RegisterTwo().SingleInstance()? Is it possible to directly or indirectly “union” two IRegistrationBuilderTLAR objects, so that configuring the result configures all the underlying registrations, or is there another way to do this?

More generally: is there a primer out there for working with the Autofac internals?

Thanks for your time.

Answer 1

Gosh, I hate answering my own Q, but all suggested alternatives seemed off-point or too complicated. Nick’s comment came the closest to engaging, but only succeeded in scaring me off Autofac internals entirely ;). I investigated, but that was overkill for my situation.

I ended up splitting the difference (as implied in my comment above), abandoning the fluent interface, but still allowing for flexible continuation of the registration by accepting the config into the method itself:

    public static void RegisterSharedChannel<T>(this ContainerBuilder builder, Func<IComponentContext, ChannelFactory<T>> @delegate, 
        Action<Autofac.Builder.IRegistrationBuilder<object, Autofac.Builder.IConcreteActivatorData, Autofac.Builder.SingleRegistrationStyle>> config)
    {
        builder.Register(c => c.Resolve<Wcf.ISharedChannel<T>>().GetChannel()).ExternallyOwned();
        //would be really nice to be able to retain the fluency of the interface, but: http://stackoverflow.com/questions/8608415/fluent-configuration-of-multiple-registrations
        //this should suffice for now...
        var facreg = builder.Register(c => @delegate(c));
        var sharereg = builder.RegisterType<Wcf.SharedChannel<T>>().AsImplementedInterfaces();
        config(facreg);
        config(sharereg);
    }

The calling syntax isn’t as pretty (e.g.:

builder.RegisterSharedChannel(c => BuildChannelFactory(...), r => r.SingleInstance());

but all (most of?) the flexibility is still there.