vb.net 在dll里如何实现回调

Question

用vb.net语言写个dll,在dll里如何执行主程序里的一个自定义函数

Answer 1

可以在dll中提供委托函数，让主程序将其自定义函数注册到dll的委托函数中。然后在dll中调用委托函数实现对主程序的自定义函数调用。
声明一个module用于传递声明委托

Module myModule
    '声明委托
    Public myaction As Func(Of String, String)

    '创建委托
    'Public Delegate Function myact(str As String) As Integer
    'Public Delegate Sub myact2(str As String)
    '声明委托
    'Public myaction As myact
    'Public myaction2 As myact2

    Public Mainf As New MainForm
    Sub Main()

        Application.EnableVisualStyles()  '启用xp视觉样式
        Application.Run(Mainf) '加不加()都是调用默认构造函数，最好加
    End Sub
End Module

主程序

Public Class MainForm
    Dim childF As New ChildForm

    Private Function Mycall(str As String) As String
        TextBox1.Text = str
        Return 123
    End Function

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        childF.Show()
        childF.RSMsg = TextBox1.Text
        myaction = AddressOf Mycall
        'myaction2 = New myact2(AddressOf Mycall)
    End Sub
End Class

dll子程序：

Public Class ChildForm
    Public Property RSMsg() As String
        Get
            Return TextBox1.Text
        End Get
        Set(ByVal Value As String)
            TextBox1.Text = Value
        End Set
    End Property

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim num As Integer
        num = myaction.Invoke(RSMsg)

    End Sub
End Class