C#

Coder For Hire wrote:

switch statement that returns an instance.

Coder For Hire wrote:

it involves a lot of classes that create other classes.

public interface IExportMetadata
{
   string Name { get; }
}

public class MyAttribute : ExportAttribute
{
   public string Name { get; set; }

   public MyAttribute(Type type, string name) : base(type) { Name = name; }
}

[My(typeof(IMyInterface),"Test!")]
public class MyClass
{
   ...
}

public static class MefProvider
{
   private static readonly Lazy<CompositionContainer> _container =
            new Lazy<CompositionContainer>(() => new CompositionContainer(_catalog.Value));

   private static readonly Lazy<AggregateCatalog> _catalog =
            new Lazy<AggregateCatalog>(() => new AggregateCatalog(
            new AssemblyCatalog(Assembly.GetExecutingAssembly())));

   public static CompositionContainer Container
   {
       get { return _container.Value; }
   }

   public static T Provide<T>(string name = "")
   {
       if (string.IsNullOrWhiteSpace(name))
       {
           return _container.Value.GetExportedValueOrDefault<T>();
       }
       return Container.GetExports<T, IExportMetadata>()
           .Where(x => x.Metadata.Name
           .Equals(name, StringComparison.InvariantCultureIgnoreCase))
           .Select(y => y.Value)
           .FirstOrDefault();
    }
}

MySettings settings = Application.Current.Properties["Settings"] as MySettings;

public static ConcurrentDictionary<string,object> MySettings = new ConcurrentDictionary<string,object>();
// ...
MySettings[ "Now" ] = DateTime.Now;

public class MyStaticSingleton
{
   #region Instance Control
       private static Lazy<MyStaticSingleton> _instance = 
          new Lazy<myStaticSingleton>(() => new MyStaticSingleton());

       private MyStaticSingleton(){}

       public static MyStaticSingleton Instance
       {
          get { return _instance.Value; }
       }
   #endregion

   #region Properties, methods, etc...

   ...
   #endregion
}