摘要：
class Space : IEnumerable> { public T Filler { get { if (!ed) { ed = true; return (filler = Top.create()); } return fil... 阅读全文
摘要：
class Space : IEnumerable { public object Filler { get { return filler ?? (filler = Top.create()); } } public Space Upper { get; protected set; } public Sp... 阅读全文