为什么？重新声明东西来实现接口？！在VB.NET中

发布于 2024-08-12 04:28:06 字数 454 浏览 6 评论 0原文

我在 VB.NET v2 中工作，

我有一个接口 IMyInterface，该接口实现了一个方法 MyMethod。

我有一个对象MyObjectBase。该对象包含一个（相同的）方法MyMethod。

1) 如果现在我MyObject Inherits MyObjectBase Implements IMyInterface 需要重新定义吗？（阴影，覆盖）MyMethod在 MyObject 类中？

2) 如果我有一个 MyEvent event 代替 MyMethod 方法，现在该怎么办？

谢谢。

原文

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

嘦怹 2024-08-19 04:28:06

在 VB.NET 中，您需要手动将接口契约与实现关联起来。看一下下面的示例：

Interface MyInterface
    Sub Foo()
End Interface

Class TestClass
    Implements MyInterface

    Public Sub Test() Implements MyInterface.Foo
        Console.WriteLine("Test")
    End Sub

    Public Sub Foo()
        Console.WriteLine("Foo")
    End Sub
End Class

然后看一下下面的代码及其输出：

Dim x As New TestClass()
x.Foo()                           ' Output: Foo '
Dim y As MyInterface = x
y.Foo()                           ' Output: Test '

这样做的优点是实现接口不会限制您按照自己的意愿命名函数。缺点是您必须使用 Implements 关键字显式地将类方法与接口声明关联起来。

关于解释就这么多。现在让我解决您的问题：由于您无法使 Button 实现 IVisibleChanged，因此您可以执行以下操作：

Private Event MyVisibleChanged() Implements IVisibleChanged.VisibleChanged

Private Sub RethrowVisibleChanged() Handles MyBase.VisibleChanged
    RaiseEvent MyVisibleChanged()
End Sub

MyBase 是引用超类的 VB.NET 关键字。同样，对于MyMethod，您可以这样做

Private Sub MyInterfaceMethod() Implements IMyInterface.Method
    MyBase.Method()
End Sub

这可能看起来像是不必要的额外工作，但在某种程度上，它是有意义的：Button.VisibleChanged和IVisibleChanged .VisibleChanged 可能是具有两种完全不同语义的事件，只是碰巧具有相同的名称（毕竟 Button 没有实现 IVisibleChanged）。通过您的代码，您可以显式地在这两者之间创建连接。

In VB.NET, you need to manually associate your interface contract with your implementations. Have a look at the following example:

Interface MyInterface
    Sub Foo()
End Interface

Class TestClass
    Implements MyInterface

    Public Sub Test() Implements MyInterface.Foo
        Console.WriteLine("Test")
    End Sub

    Public Sub Foo()
        Console.WriteLine("Foo")
    End Sub
End Class

Then have a look at the following code and its output:

Dim x As New TestClass()
x.Foo()                           ' Output: Foo '
Dim y As MyInterface = x
y.Foo()                           ' Output: Test '

This has the advantage that implementing an interface does not restrict you in naming your function as you want to. The disadvantage is that you have to explicitly associate your class methods with your interface declarations using the Implements keyword.

So much about an explanation. Now let me get to your problem: Since you cannot make Button implement IVisibleChanged, you can do something like that:

Private Event MyVisibleChanged() Implements IVisibleChanged.VisibleChanged

Private Sub RethrowVisibleChanged() Handles MyBase.VisibleChanged
    RaiseEvent MyVisibleChanged()
End Sub

MyBase is a VB.NET keyword referring to the superclass. Likewise, in the case of MyMethod, you can do

Private Sub MyInterfaceMethod() Implements IMyInterface.Method
    MyBase.Method()
End Sub

This might seem like unnecessary extra work, but in a way, it makes sense: Button.VisibleChanged and IVisibleChanged.VisibleChanged might be events with two completely different semantics, who just happen to have the same name (after all Button does not implement IVisibleChanged). With your code, you explicitly create a connection between those two.

回复收藏 0 原文