attributesclassusec.vb

来自「大名鼎鼎的mono是.NET平台的跨平台（支持linux」· VB 代码 · 共 40 行

'Author: Ritvik Mayank <[e-mail]>
'Copyright (C) 2005 Novell Inc. (http://www.novell.com)
' multiple-use for derived takes both the attributes

Imports System

<AttributeUsage(AttributeTargets.Class, AllowMultiple:=True, _
                Inherited:=True)> _
Class MultiUseAttribute
    Inherits System.Attribute
    Public Sub New(ByVal Value As Boolean)
    End Sub
End Class

<AttributeUsage(AttributeTargets.Class, Inherited:=True)> _
Class SingleUseAttribute
    Inherits Attribute
    Public Sub New(ByVal Value As Boolean)
    End Sub
End Class

<SingleUse(True), MultiUse(True)> Class Base
End Class

<SingleUse(False), MultiUse(False)> _
Class Derived
    Inherits Base
End Class

Module Test
    Function Main() As Integer
        Dim type As Type = GetType(Derived)
        Dim arr() As Object = _
        type.GetCustomAttributes(GetType(Attribute), True)
        If arr.Length <> 3 Then
            Throw New Exception("multiple-use attribute is inherited on a derived type can take both attributes. expected total attributes = 3 but got " & arr.Length)
        End If
    End Function
End Module