vb.net 创建作为参数给出的类型的新实例
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Create a new instance of a type given as parameter
提问by stex
I've searched for an answer and found some c#-examples, but could not get this running in vb.net:
我搜索了一个答案并找到了一些 c#-examples，但无法在 vb.net 中运行：
I thought of something like the following:
我想到了以下内容：
public function f(ByVal t as System.Type)
dim obj as t
dim a(2) as t
obj = new t
obj.someProperty = 1
a(0) = obj
obj = new t
obj.someProperty = 2
a(1) = obj
return a
End Function
I know, I can create a new instance with the Activator.Create... methods, but how to create an array of this type or just declare a new variable? (dim)
我知道，我可以使用 Activator.Create... 方法创建一个新实例，但是如何创建这种类型的数组或仅声明一个新变量？（暗淡）
Thanks in advance!
提前致谢！
回答by JDC
Personaly I like this syntax much more.
我个人更喜欢这种语法。
Public Class Test(Of T As {New})
Public Shared Function GetInstance() As T
Return New T
End Function
End Class
Or if you want to limit the possible types:
或者，如果您想限制可能的类型：
Public Class Test(Of T As {New, MyObjectBase})
Public Shared Function GetInstance() As T
Return New T
End Function
End Class
回答by M.A. Hanin
It really depends on the type itself. If the type is a reference type and has an empty constructor(a constructor accepting zero arguments), the following code should create an insance of it: Using Generics:
这实际上取决于类型本身。如果类型是引用类型并且有一个空的构造函数（一个接受零参数的构造函数），下面的代码应该创建它的一个实例：使用泛型：
Public Function f(Of T)() As T
Dim tmp As T = GetType(T).GetConstructor(New System.Type() {}).Invoke(New Object() {})
Return tmp
End Function
Using a type parameter:
使用类型参数：
Public Function f(ByVal t As System.Type) As Object
Return t.GetConstructor(New System.Type() {}).Invoke(New Object() {})
End Function
