IoC, Implement the IoC within 33 lines of code, http://kenegozi.com/blog/2008/01/17/its-my-turn-to-build-an-ioc-container-in-15-minutes-and-33-lines

IoC.cs

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()); 
  }
}



// Plugin
public interface IFileSystemAdapter { }

public class FileSystemAdapter : IFileSystemAdapter { }

public interface IBuildDirectoryStructureService { }

public class BuildDirectoryStructureService : IBuildDirectoryStructureService{ 
  IFileSystemAdapter fileSystemAdapter; 

  public BuildDirectoryStructureService(IFileSystemAdapter fileSystemAdapter) { 
    this.fileSystemAdapter = fileSystemAdapter; 
  }
}


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