public override void Delete(Depositor despositor)
{
observers.Remove(despositor);
}
public abstract void Add(Depositor despositor); //增加客户
public abstract void Delete(Depositor despositor); //删除客户
public override void Add(Depositor despositor)
{
//新增删除都需要判断是否存在客户
//这边简化一些
observers.Add(despositor);
}
public abstract void Add(Depositor despositor); //增加客户
