Some fun with private ctors

Factory.cs

public static class Factory<T> where T : class 
{
	private static readonly Func<T> FactoryFn;

	static Factory()
	{
		//FactoryFn = CreateUsingActivator();

		FactoryFn = CreateUsingLambdas();
	}

	private static Func<T> CreateUsingActivator()
	{
		var type = typeof(T);

		Func<T> f = () => Activator.CreateInstance(type, true) as T;

		return f;
	}

	private static Func<T> CreateUsingLambdas()
	{
		var type = typeof(T);

		var ctor = type.GetConstructor(BindingFlags.Instance | BindingFlags.CreateInstance | BindingFlags.NonPublic, null, new Type[] { }, null);

		var ctorExpression = Expression.New(ctor);
		return Expression.Lambda<Func<T>>(ctorExpression).Compile();
	}

	public static T Create(Action<T> init)
	{
		var instance = FactoryFn();

		init(instance);

		return instance;
	}
}

Model.cs

public interface IPerson
{
	string Name { get; set; }
}

public class Person : IPerson 
{
	public string Name { get; set; }

	private Person() { }
}

Program.cs

class Program
{
    static void Main(string[] args)
    {
		//TOUCH ONCE BEFORE TIMING
		var touchedPerson = Factory<Person>.Create(p => p.Name = "Daniel");

		for (var a = 0; a < 5; a++)
		{
			var sw = Stopwatch.StartNew();
			for (int c = 0; c < 100000; c++)
			{
				var person = Factory<Person>.Create(p => p.Name = "Daniel");
				var n = person.Name;
			}
			sw.Stop();
			Console.WriteLine(sw.Elapsed.TotalMilliseconds);
		}
		Console.ReadKey();
    }
}