Allow decorators to take relationship types

[YairHalberstadt]

I have an implementation of an interface which cannot be resolved too early in the application lifetime, and so must be resolved lazily.

Because this is used by hundreds of components, rather than use Lazy, I've created a lazy wrapper over the interface, and would like to register it.

public class LazyMyInterface : IMyInterface
{
     private readonly Lazy<IMyInterface> _myInterface;

     public LazyInterface(Lazy<IMyInterface> myInterface) => _myInterface = myInterface;

     private IMyInterface MyInterface => _myInterface.Value;

     public void MyMethod => MyInterface.MyMethod();
}

However I can't see any way to register it. Registering it directly will lead to an infinite loop, as it will replace the implementation of IMyInterface.

Registering it as a decorator causes the eager evaluation of MyInterface.

I think this could be resolved by allowing decorators to take relationship types of the interface.

[nblumhardt]

Hi! This is some tricky territory - I suspect you may be able to do this by implementing and plugging in your own IRegistrationSource, but you'll need to check out https://github.com/autofac/Autofac/blob/develop/src/Autofac/Features/LazyDependencies/LazyRegistrationSource.cs and tinker with it to catch any gotchas. Good luck!

[alexmg]

Closing as a duplicate of #967 which has a lot more discussion. It certainly is tricky territory.