.net - 如何根据传递给 VB.NET 泛型方法的类型执行条件逻辑

Question

我想创建一个创建类实例的 VB.NET 通用工厂方法（作为控制容器的本土反转）。如果我将接口 IDoSomething 作为通用参数传递，我想返回一个 DoSomething 的实例（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 

但是这段代码无法编译。

Answer 1

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

Answer 2

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