静态/在VB.NET和C＃的知名度共享 [英] static/Shared in VB.NET and C# visibility

问题描述

我也遇到这样的情况在VB.NET和C＃（.NET2）与静态/共享成员的可见性。在我看来有点怪在VB.NET：

I have faced with a situation in VB.NET and C# (.NET2) with the visibility of the static/shared members. It seems to me a little strange in VB.NET:

    public class A 
    {
        private static A instance;
        public static A Instance 
        {
            get { return instance; }
        }

        public string Name { get { } }
    }

使用的： A.Instance.Name // 唯一的名字是看得见

VB.NET：

Public Class A
  Private Shared _instance As A

  Public Shared ReadOnly Property Instance() As A
    Get
      Return _instance
    End Get
  End Property


  Public ReadOnly Property Name() As String
    Get
      Return ""
    End Get
  End Property

End Class

使用的：

A.Instance.Instance.Instance.Instance...

//共享成员的行为就像一个班公一个我可以重复它无限..

这是微软疏忽或VB.NET功能？

is this a Microsoft oversight or a VB.NET "feature"?

推荐答案

这不是一个疏忽，但你的VB code 将触发警告，这显然意味着：不使用这个符号。

It's not an oversight but your VB code will trigger a warning, which plainly means: do not use this notation.

在VB中，静态成员的可以的可以通过一个实例访问，因为严格来说，VB的没有静态 ：VB有关键字共享，这意味着该成员的共享的所有实例之间，相对于静态，其中一个成员不属于的任意的实例。

In VB, static members can be accessed via an instance, since strictly speaking, VB doesn’t have static: VB has the keyword Shared, meaning that the member is shared between all instances, as opposed to static where a member doesn’t belong to any instance.

现在，这是这些关键字之间的语义差别。它只是恰巧，这两个不同的语义往往有相同的效果。

Now, this is a semantical distinction between those keywords. It just so happens that these two distinct semantics tend to have the exact same effect.

当然，静态在C＃中是共享在VB.NET，但他们的遗产是不同的， VB的共享只是有不同的历史，因此历史上有不同的含义。通过的这个的意义，它使绝对意义上通过一个实例访问共享的成员。

Of course, static in C# is today identical to Shared in VB.NET but their legacy is different and VB’s Shared simply has a different history and therefore historically a different meaning. With this meaning, it makes absolutely sense to access Shared members via an instance.

这也是情理之中的时候用选项严格关（弱类型）一起使用：在这里，你有时的不知道的变量的类型但你仍然可能需要访问一个共享成员。现在，你有没有选择，只能使用一个实例来访问：

It also makes sense when used together with Option Strict Off (loose typing): here, you sometimes don’t know a variable’s type but you still might want to access a Shared member. Now, you’ve got no choice but to use an instance to access it:

Option Strict Off
' … '
Dim o As Object = New A()
' Somewhere else, we want to access a static member of A but we don’t know A: '
Dim instance = o.Instance

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