分岐が多数ある機能の実装方法

static void Main(string[] args)
{
	Action action = new ActionA();
	while ((action = action.Run()) != null) ;
}

abstract class Action
{
	public abstract Action Run();
}

class ActionA : Action
{
	public ActionA() { }

	public override Action Run()
	{
		ObjectA obj;
		//処理
		return new ActionB(obj);
	}
}

class ActionB : Action
{
	ObjectA objectA;

	public ActionB(ObjectA obj) { }

	public override Action Run()
	{
		int i;
		bool flg;
		//処理
		if(flg) return new ActionC(objectA, i);
		else return new ActionD();
	}
}

class ActionC : Action
{
	public ActionC(ObjectA obj, int i) { }

	public override Action Run()
	{
		//処理
		return new ActionD();
	}
}

class ActionD : Action
{
	public ActionD() { }

	public override Action Run()
	{
		//処理
		return null;
	}
}

class ObjectA { }