Question

好的，一些继承的代码：我有一个具有完整权限的结构：

public structure Perms
    dim writeStaff as Boolean
    dim readStaff as Boolean
    dim writeSupervisor as Boolean
    dim readSuperVisor as Boolean
    ' ... and many more
End Structure

我想要一个像我这样创建的函数canDo：

public function canDo(p as Perms, whichOne as String) as boolean
    Dim b as System.Reflection.FieldInfo
    b = p.GetType().GetField(whichOne)
    return b
end function

我用预先填充的结构和“writeSupervisor”参数调用canDo

在debug中，b显示为{Boolean writeSupervisor}，但是当我尝试将b作为布尔值返回时，我得到错误：“System.Reflection.FieldInfo”类型的值无法转换为“Boolean”。

我是如何通过元素名称和测试/比较/返回值“索引”到结构中的？

Answer 1

您需要调用GetValue对象的FieldInfo方法来获取字段值。

Public Function canDo(p As Perms, whichOne As String) As Boolean
    If (Not String.IsNullOrEmpty(whichOne)) Then
        Dim info As FieldInfo = p.GetType().GetField(whichOne)
        If (Not info Is Nothing) Then
            Dim value As Object = info.GetValue(p)
            If (TypeOf value Is Boolean) Then
                Return DirectCast(value, Boolean)
            End If
        End If
    End If
    Return False
End Function

我还建议你阅读：Visual Basic Naming Conventions。

通过变量名访问VB.Net结构元素

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