Implementing EnrichWith(of StructureMap) with Castle

Tuna Toksoz — Tue, 14 Jul 2009 13:30:00 GMT

UPDATE: This facility made its way into Castle Microkernel, with name OnCreateFacility. I also made it possible to specify more than one actions.

In one of Joshua Flanagan's recent post he mentioned about how they handle application configuration and I have to say that I liked their way. I also liked how SM can post-modify an object created, and looked for a way to do it in Castle. As many other stuff, I was able to achieve the same effect with a custom Facility.

If I go further in the details, I had to catch ComponentCreated event of Kernel.

public class EnrichWithFacility:AbstractFacility
{
	public const string ExtendWithPropertyKey = "extendwith";
	protected override void Init()
	{
		Kernel.ComponentCreated += new Kernel_ComponentCreated;
	}
	void Kernel_ComponentCreated(ComponentModel model, object instance)
	{
		if(model.ExtendedProperties.Contains(ExtendWithPropertyKey))
		{
			var action = model.ExtendedProperties[ExtendWithPropertyKey] as ExtendComponentDelegate;
			action(this.Kernel, instance);
		}
	}
}

Whenever a component is created, I will catch it and ask if there is any EnrichWith registered for the ComponentModel, and if there is any, invoke the action.

I also added a fluent registration extensions (Castle style!) in order to make it easy to register enrichments.

container.Register(Component.For<IService>().ImplementedBy<MyService>()
			 .EnrichWith((kernel, instance) => ((IService) instance).I++));

The code for the facility, fluent registration interface,and the tests can be found on our never-ending blog engine, BlogSharp codebase.

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Tuna Toksoz : windsor

Implementing EnrichWith(of StructureMap) with Castle