Neat Tricks with StructureMap

I’ve been getting a crash course in StructureMap the past 2 weeks. It’s been going pretty well especially when you consider that the author/maintainer sits next to me every day 🙂

We’ve been using the new 2.5-ish trunk code and there are some cool features I’d like to share with you and maybe get you pumped about the upcoming 2.5 release.

Auto-registration of obvious types

This one is particularly cool since most of the types registered in your container are ISomeService with an associated SomeService implementation.

Simply put:  If you have a class Foo that implements interface IFoo, StructureMap, if asked to do so, will auto-register Foo as the default concrete type for plugin family IFoo. No config necessary!  Phew… just saved the world some serious angle brackets tax there. Every bit counts, trust me — I came from a SpringFramework.NET background which is rich in its XML configuration.

Convention-based Discovery/Registration

When calling StructureMapConfiguration.ScanAssemblies(), you can now provide your own type registration conventions in addition to the default one. For example:

   1: StructureMapConfiguration.ScanAssemblies()

   2:     .With<DefaultConventionScanner>()

   3:     .With<YourCustomConvention>();

StructureMap will call a method on YourCustomConvention for each Type it finds, allowing you to do fancy things such as:

   1: if (CanBeCast(typeof (IController), type))

   2: {

   3:     string name = type.Name.Replace("Controller", "").ToLower();

   4:     registry.AddInstanceOf(typeof (IController), new ConfiguredInstance(type).WithName(name));

   5: }

This allows us, in our MVC application to register all of our controllers using their short name (i.e. LoginController -> “login”) so that they can be loaded via our custom StructureMapControllerFactory.

On-the-fly Dependency Satisfaction

This one comes in handy, but I feel a little dirty when I use it — as though I’m cheating IoC somehow. It’s cool nonetheless:

I have a service that takes the current HttpContext from ASP.NET in order to function. I then needed to pass this service into yet another service in order to construct it properly. There are a couple different ways of accomplishing this, but for this example, I’ll do it this way just to illustrate the point:

   1: ObjectFactory

   2:     .With<ISecurityContext>(new HttpSecurityContext(HttpContext.Current))

   3:     .GetInstance<AuthenticationService>();

In order to get my AuthenticationService instance, I needed an ISecurityContext — particularly the HttpSecurityContext which takes the current HttpContext.

More to Come

As I learn more I’ll post ’em.  Also, I think Jeremy has a few more tricks up his sleeve before the release so keep an eye on his blog and the StructureMap web site for more news.