这里是 Msgbox 的源代码。如您所见,在调用 MessageBox.Show 之前它并没有做任何特别有趣的事情。
<MethodImpl(MethodImplOptions.NoInlining), HostProtection(SecurityAction.LinkDemand, Resources:=HostProtectionResource.UI)> _
Public Shared Function MsgBox(ByVal Prompt As Object, ByVal Optional Buttons As MsgBoxStyle = 0, ByVal Optional Title As Object = new Object()) As MsgBoxResult
Dim owner As IWin32Window = Nothing
Dim text As String = Nothing
Dim titleFromAssembly As String
Dim vBHost As IVbHost = HostServices.VBHost
If (Not vBHost Is Nothing) Then
owner = vBHost.GetParentWindow
End If
If ((((Buttons And 15) > MsgBoxStyle.RetryCancel) OrElse ((Buttons And 240) > MsgBoxStyle.Information)) OrElse ((Buttons And &HF00) > MsgBoxStyle.DefaultButton3)) Then
Buttons = MsgBoxStyle.OkOnly
End If
Try
If (Not Prompt Is Nothing) Then
[text] = CStr(Conversions.ChangeType(Prompt, GetType(String)))
End If
Catch exception As StackOverflowException
Throw exception
Catch exception2 As OutOfMemoryException
Throw exception2
Catch exception3 As ThreadAbortException
Throw exception3
Catch exception9 As Exception
Throw New ArgumentException(Utils.GetResourceString("Argument_InvalidValueType2", New String() { "Prompt", "String" }))
End Try
Try
If (Title Is Nothing) Then
If (vBHost Is Nothing) Then
titleFromAssembly = Interaction.GetTitleFromAssembly(Assembly.GetCallingAssembly)
Else
titleFromAssembly = vBHost.GetWindowTitle
End If
Else
titleFromAssembly = Conversions.ToString(Title)
End If
Catch exception4 As StackOverflowException
Throw exception4
Catch exception5 As OutOfMemoryException
Throw exception5
Catch exception6 As ThreadAbortException
Throw exception6
Catch exception13 As Exception
Throw New ArgumentException(Utils.GetResourceString("Argument_InvalidValueType2", New String() { "Title", "String" }))
End Try
Return DirectCast(MessageBox.Show(owner, [text], titleFromAssembly, (DirectCast(Buttons, MessageBoxButtons) And DirectCast(15, MessageBoxButtons)), (DirectCast(Buttons, MessageBoxIcon) And DirectCast(240, MessageBoxIcon)), (DirectCast(Buttons, MessageBoxDefaultButton) And DirectCast(&HF00, MessageBoxDefaultButton)), (DirectCast(Buttons, MessageBoxOptions) And DirectCast(-4096, MessageBoxOptions))), MsgBoxResult)
End Function