ISubscribe

I believe Jimmy Bogard has a similar technique (IHandler<T>) with ASP .Net MVC but I thought I would still share the convention I’ve been using to wire up subscriptions to the Prism Event Aggregator.

Whenever an object is built with StructureMap, it goes through all the TypeInterceptors. I have a SubscriptionTypeInterceptor:

public class SubscriptionInterceptor : TypeInterceptor
    {
        public object Process(object target, IContext context)
        {
            var eventAggregator = context.GetInstance<IEventAggregator>();

            // Get interface ISubscribe<E>
            var interfaces = target.GetType().GetInterfaces().Where(i => i.Name.Contains("ISubscribe"));

            foreach (var type in interfaces)
            {
                // typeof(E)
                var eventType = type.GetGenericArguments()[0];

                var setupMethod = GetType().GetMethod("Setup");
                setupMethod.MakeGenericMethod(eventType).Invoke(this, new[] { target, eventAggregator });
            }

            return target;
        }

        public bool MatchesType(Type type)
        {
            return type.ImplementsInterfaceTemplate(typeof(ISubscribe<>));
        }

        public void Setup<T>(ISubscribe<T> subscriber, IEventAggregator eventAggregator)
        {
            eventAggregator
                .GetEvent<CompositePresentationEvent<T>>()
                .Subscribe(subscriber.Subscribe);
        }
    }

So it finds all the ISubscribe<T> interfaces the target implements and then subscribes the target to the event T in the event aggregator.

public interface ISubscribe<E>
{
    void Subscribe(E e);
}

A simple example of usage:

public class SecurityController : IController,
                                  ISubscribe<RequestUserLoginEvent>
{
    public void Subscribe(RequestUserLoginEvent e)
    {
        Publish.Event().ShowModal<IRequestUserLoginViewModel>();
    }
}