我想创建一个VB.NET通用工厂方法，该方法创建类的实例(作为控件容器的本地反转)。如果我将接口IDoSomething作为通用参数传递，我想返回DoSomething的一个实例(实现IDoSomething)。我无法弄清楚if语句的语法。我想写一些类似的东西：

Public Function Build(Of T) as T  
    If T Is IDoSomething then  
        Return New DoSomething()  
    ElseIf T Is IAndSoOn Then  
        Return New AndSoOn()  
    Else  
        Throw New WhatWereYouThinkingException("Bad")  
    End If  
End Sub

但是此代码无法编译。

解决方案

Public Function Build(Of T) As T
  Dim foo As Type = GetType(T)

  If foo Is GetType(IDoSomething) Then
    Return New DoSomething()
  ...
  End If
End Function

Public Function Build(Of T) as T  
    If T.gettype Is gettype(IDoSomething) then  
        Return New DoSomething()  
    ElseIf T.gettype Is gettype(IAndSoOn) Then  
        Return New AndSoOn()  
    Else  
        Throw New WhatWereYouThinkingException("Bad")  
    End If  
End Sub