Autofac委托工厂和RegisterGeneratedFactory()的区别

Question

Accordding to autofac doc , when a service constructor has duplicate types like the following:

public class DuplicateTypes
{
  public DuplicateTypes(int a, int b, string c)
  {
    // ...
  }
}

Func<X,Y,B> will not work, you should use a custom delegate type instead:

public delegate DuplicateTypes FactoryDelegate(int a, int b, string c);

with the delegate factory,we can resolve the FactoryDelegate without registering anything else:

builder.RegisterType<DuplicateTypes>();
var container = builder.Build();
var scope = container.BeginLifetimeScope();
var func = scope.Resolve<FactoryDelegate>();

But in the autofac doc,we can register that delegate using RegisterGeneratedFactory():

builder.RegisterType<DuplicateTypes>();
builder.RegisterGeneratedFactory<FactoryDelegate>(new TypedService(typeof(DuplicateTypes)));

after that we can also resolve the FactoryDelegate.

var func = scope.Resolve<FactoryDelegate>();

So what's the difference of delgate factory and RegisterGeneratedFactory? Is RegisterGeneratedFactory redundant? If not, which case suites RegisterGeneratedFactory?

Answer 1

The short version is you really don't need RegisterGeneratedFactory ever. If you look at the API docs on it , you can see it says:

These features are in this namespace because they will remain accessible to applications originally written against Autofac 1.4. In Autofac 2, this functionality is implicitly provided and thus making explicit registrations is rarely necessary.

So, basically, it's there for people who were using it before so we don't break them, but we're into Autofac 6 now and there's no value in using it in new applications.

We should probably look at deprecating those methods in Autofac so we can remove them in the next major release or so and reduce confusion.