Using Open Generics with Funq

Question

I have the following interface:

public interface IWriter<in TId, TViewModel>

For which there are a number of different implementations such as:

public class RedisWriter<TId, TViewModel> : IWriter<TId, TViewModel> 

I'd like to be able to inject an instance of this class into the constructor of a service:

public class MyService : Service
{
    private readonly IWriter<Guid, OrderViewModel> _writer;

    public MyService(IWriter<Guid, OrderViewModel> writer)
    {
        _writer = writer;
    }
}

Notice that generic type parameters are closed over where an instance is required.

I can't see any way to do this in Funq. Is it possible? Or do other IOCs allow this kind of use?

Answer 1

Funq does not support building up closed implementations based on open-generic registrations. With Funq you will have to explicitly register all closed-generic implementations that the application requires. For instance:

c.Register<IWriter<Guid, OrderViewModel>>(c => new RedisWriter<Guid, OrderViewModel>());
c.Register<IWriter<int, UserViewModel>>(c => new RedisWriter<int, UserViewModel>());

do other IOCs allow this kind of use?

Yes, all the popular DI libraries support this, such as Simple Injector, Autofac, Castle Windsor, Ninject and StructureMap.