Last night I've built a nice new tool called StaticMapGenerator which is used to generate a typed static resources site-map for ASP.NET sites (works for MonoRail, ASP.NET MVC and even WebForms).

I'll blog about it on a separate post in details.

Since I didn't want any dependency (but .NET 2.0 runtime) for the generator and the generated code, I couldn't use Windsor to IoC. That calls for a hand rolled simple IoC implementation

Ayende has already done it in 15 lines, but I wanted also to automagically set dependencies and have a simpler registration model.

so I've quickly hacked together a configurable DI resolver (a.k.a. IoC container) in 15 Minutes and 33 Lines Of Code. Call me a sloppy-coder, call me whadever-ya-like. It just works.

static class IoC 
{ 
   static readonly IDictionary<Type, Type> types = new Dictionary<Type, Type>(); 
   
   public static void Register<TContract, TImplementation>() 
   {
      types[typeof(TContract)] = typeof(TImplementation); 
   }
   
   public static T Resolve<T>() 
   {
      return (T)Resolve(typeof(T));
   }

   
   public static object Resolve(Type contract)
   {
      Type implementation = types[contract];
   
      ConstructorInfo constructor = implementation.GetConstructors()[0];
   
      ParameterInfo[] constructorParameters = constructor.GetParameters(); 
   
      if (constructorParameters.Length == 0)
         return Activator.CreateInstance(implementation);
   
      List<object> parameters = new List<object>(constructorParameters.Length); 
   
      foreach (ParameterInfo parameterInfo in constructorParameters) 
         parameters.Add(Resolve(parameterInfo.ParameterType));
   
      return constructor.Invoke(parameters.ToArray());
   }
}

Ok, I've cheated. You'd need using statements too, but you can see that I was generous enough with newlines ...

Usage:

Given those:

public interface IFileSystemAdapter { }
 
public class FileSystemAdapter : IFileSystemAdapter { }
 
public interface IBuildDirectoryStructureService { }
 
public class BuildDirectoryStructureService : IBuildDirectoryStructureService
{
   IFileSystemAdapter fileSystemAdapter;
   public BuildDirectoryStructureService(IFileSystemAdapter fileSystemAdapter)
   {
      this.fileSystemAdapter = fileSystemAdapter;
   }
}

You can do that:

IoC.Register<IFileSystemAdapter, FileSystemAdapter>();
 
IoC.Register<IBuildDirectoryStructureService, BuildDirectoryStructureService>(); 
 
IBuildDirectoryStructureService service = IoC.Resolve<IBuildDirectoryStructureService>();

You need not worry about supplying the BuildDirectoryStructureService with an implementation for the service it depends on, but only to register an implementation for that service.