Question

我认为接口不仅是一组成员，而且还是一个“契约”，它强制实现保持接口文档中指定的限制。例如：

interface IDevice
{
    bool IsActive { get; }

    int Address { get; }

    /// <summary>
    /// Raised when (IsActive == false)
    /// and device was activated
    /// </summary>
    event Action Activated;

    /// <summary>
    /// Raised when (IsActive == true)
    /// and device was deactivated
    /// </summary>
    event Action Deactivated;

    /// <summary>
    /// Raised when (IsActive == false)
    /// and Address was changed
    /// </summary>
    event Action<int> AddressChanged;
}

此外，我的用户对激活/停用过程不感兴趣，但想知道Address何时会发生变化，因此，在ISP的带领下，我创建了一个新界面：

interface IAddressee
{
    int Address { get; }

    /// <summary>
    /// Raised when Address was changed
    /// </summary>
    event Action<int> AddressChanged;
}

现在IDevice看起来像：

interface IDevice : IAddressee
{
    bool IsActive { get; }

    /// <summary>
    /// Raised when (IsActive == false)
    /// and device was activated
    /// </summary>
    event Action Activated;

    /// <summary>
    /// Raised when (IsActive == true)
    /// and device was deactivated
    /// </summary>
    event Action Deactivated;
}

如您所见，IDevice的合同已经失去了一个条件：AddressChanged事件只有在设备处于非活动状态时才会引发（IsActive == false）。

我无法在IAddressee接口中记录它，因为它不依赖于IDevice，并且可以存在非设备实现。

这种情况是否正常？你会采取什么措施来强制IDevice实现纠正行为？

我是合约概念的新手，所以请消除我的幻想和怀疑

Answer 1

在这种情况下，抽象条件就可以了。它们表达的内容可能取决于顶级课程中没有的信息。稍后以适合特定后代的方式实施该条件。在你的例子中

interface IAddressee
{
    int Address { get; }

   /// <summary>
   /// Can Address be changed?
   /// </summary>
   bool IsAddessChangeable { get; };

    /// <summary>
    /// Raised when (IsAddessChangeable == true)
    /// and Address was changed
    /// </summary>
    event Action<int> AddressChanged;
}

在实现IDevice的类中，查询IsAddessChangeable将在其他类中返回IsActive == false - 值取决于所需的语义。

跨界面合同

1 个答案: