是否可以在一个函数中包含一个函数?

问题描述：

是否可以在一个函数中包含一个函数?

Is it possible to have a function within a function?

像这样:

Public Class Form1
    Private Sub button1_Click(sender As Object, e As EventArgs) Handles button1.Click
        Sub anim() Handles form2.Shown
            Me.Refresh()
            Do Until Me.Location.X = 350
                form2.Location = New Point(Me.Location.X + 1, 250)
                ' System.Threading.Thread.Sleep(0.5)
            Loop
            form2.close()
        End Sub
    End Sub
End Class

答

在 VB.NET 中不可能有完全成熟的嵌套函数定义.该语言确实支持看起来很像嵌套函数的多行 lambda 表达式:

It is not possible to have a fully fledged nested function definition in VB.NET. The language does support multi-line lambda expressions which look a lot like nested functions:

Private Sub button1_Click(sender As Object, e As EventArgs) Handles button1.Click
  Dim anim =
    Sub()
      Me.Refresh()
      ...
    End Sub
End Sub

虽然有一些显着差异:

不能有 Handles 子句.
不能是 Implements 或 Overrides.
命名的是 lambda 的实例，而不是 Sub 定义.
在这种情况下，anim 实际上是一个委托，而不是一个函数.

Cannot have a Handles clause.
Cannot be Implements or Overrides.
The instance of the lambda is named, not the Sub definition.
In this case anim is actually a delegate and not a function.

是否可以在一个函数中包含一个函数?

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