Unity Register two interfaces as one singleton

Question

how do I register two different interfaces in Unity with the same instance... Currently I am using

        _container.RegisterType<EventService, EventService>(new ContainerControlledLifetimeManager());         _container.RegisterInstance<IEventService>(_container.Resolve<EventService>());         _container.RegisterInstance<IEventServiceInformation>(_container.Resolve<EventService>()); 

which works, but does not look nice..

So, I think you get the idea. EventService implements two interfaces, I want a reference to the same object if I resolve the interfaces.

Chris

Answer 1

[2nd Edit]

Because of breaking changes in the way Unity handles registrations, the updated approach does not work anymore. The [Original answer] is the way to go again. (For more details about the changes in Unity, please refer to the link given in the comments below.)

[Edit]

The solution for doing this via XML configuration can be found here. Based on that answer I would propose a streamlined code-only approach as follows:

_container.RegisterType<IEventService, EventService>(new ContainerControlledLifetimeManager()); _container.RegisterType<IEventServiceInformation, EventService>(new ContainerControlledLifetimeManager()); bool singleton = ReferenceEquals(_container.Resolve<IEventService>(), _container.Resolve<IEventServiceInformation>()); 

This way, the EventService class itself is not published by the container. As the class should be considered an implementaion detail, this is the preferable approach.

[Original answer]

A little late an answer, but should do the trick:

_container.RegisterType<EventService>(new ContainerControlledLifetimeManager()); _container.RegisterType<IEventService, EventService>(); _container.RegisterType<IEventServiceInformation, EventService>();  bool singleton = ReferenceEquals(_container.Resolve<IEventService>(), _container.Resolve<IEventServiceInformation>()); 

Answer 2

Edit

After some feedback in the comments I've decided that Sven's answer is a much superior answer. Thanks to Chris Tavares for pointing out the technical merits.

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That's pretty much the only way to do it.

You could modify it slightly (I hate RegisterType with the same type for each generic parameter):

EventService es = _container.Resolve<EventService>(); _container.RegisterInstance<IEventService>(es); _container.RegisterInstance<IEventServiceInformation>(es); 

If one or more of your IoC children is going to request the concrete EventService type (hopefully not) you'd add one more RegisterInstance of type RegisterInstance<EventService>. Hopefully you don't need that and all of the dependent objects are asking for an IEventService, rather than an EventService.

Hope this helps, Anderson