Decorate existing registration in Autofac

Question

I have following interface and its implementations:

public interface IService
{
}

public class Service1 : IService
{
}

public class DecoratedService
{
    public DecoratedService(IService inner)
    {
    }
}

Service1 is registered in the code that I cannot change (not named registration):

builder.RegisterType<Service1>().As<IService>();

So I need to decorate this registration with my own. How can I achieve this with minimal performance impact in scope of

public class DataModule : Autofac.Module

class?

It's ok if I need to change existing IService registration with the named one (but I haven't found the way how to do it). I researched all related questions in stackoverflow but non of them gave me solution.

Answer 1

You should be able to replace the existing registration for IService in your module and provide it with a name.

builder.RegisterType<Service1>().Named<IService>("implementor");

Then register a decorator for the named service.

builder.RegisterDecorator<IService>(s => new DecoratedService(s), "implementor");

Nick has a blog post with plenty of details about the decorator support in Autofac.

http://nblumhardt.com/2011/01/decorator-support-in-autofac-2-4/