private IOrder MakeLink(Action <OrderImpl <T> > func)
{
//构造新链，传递给下一个
OrderImpl <T> sel = new OrderImpl <T>(this);
func.Invoke(sel);
return(sel);
}
/// <summary>
/// 排序字段
/// </summary>
/// <param name="sql"></param>
private OrderImpl(OrderImpl <T> _obj) : base(_obj._link_list)
{
this._order_dic = new Dictionary <string, bool>(_obj._order_dic);
if (this._link_list.FirstOrDefault(f => f is IOrder) is IOrder obj)
{
this._link_list.Remove(obj);
}
this._link_list.Add(this);
}