Question

我想创建一个VB.NET通用工厂方法来创建类的实例（作为控件容器的本土反转）。如果我将接口IDoSomething作为泛型参数传递，我想返回一个DoSomething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

但是这段代码没有编译。

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

如何根据传递给VB.NET泛型方法的类型执行条件逻辑

2 个答案: