public static Treasure CreateRandomTreasure()
{
Treasure treasure = null;
treasure_type ty = GetRandomType();
switch (ty)
{
case treasure_type.AddNode:
treasure = new AddNodeTreasure();
break;
case treasure_type.SpeedUp:
treasure = new SpeedUpTreasure();
break;
case treasure_type.SpeedDown:
treasure = new SpeedDownTreasure();
break;
default:
break;
}
return(treasure);
}
//寶物的建構子，須由子類別用 :base() 呼叫，不然不會執行，沒有找到怎麼「強制」繼承者呼叫，但暫時不理會
//這裡設為public沒有關係，因為整個Treasure是abstract（看上面第七行程式碼），不能被用來直接建立實體
public Treasure()
{
node = GetRandomNode();
type = treasure_type.AddNode;
}