Question

假设我有：

Public Class clsTest
   Public Sub New()
   End Sub

   Public Sub New(name_ As String)
      '...
   End Sub
End Class

我想扩展这个类：

<System.Runtime.CompilerServices.Extension> _
Public Sub methodA(t1 As clsTest, i As Integer)
    '...
End Sub

但我不能将构造函数扩展为：

<System.Runtime.CompilerServices.Extension> _
Public Sub New(t1 As clsTest, name_ As String, i As Integer)
    '...
End Sub

Answer 1

您cannot extend constructors有扩展方法。扩展方法与允许写入的static（VB中的shared）方法几乎相同

instanceOfMyClass.SomeExtension(someParameter)

而不是

MyClass.SomeExtension(instanceOfMyClass, someParameter)

如果你没有访问clsTest（你应该真的改变你的namings）但是你想要扩展它，你也可以创建一个继承它的新类：

Public Class Foo ' consider this as your clsTest
    Public Sub New()
    End Sub
    Public Property Name As String
    Public Property Number As Int32
    Public Sub New(name As String)
        Me.Name = Name
    End Sub
End Class

Public Class Bar
    Inherits Foo

    Public Sub New(name As String, i As Integer)
        MyBase.Name = name
        MyBase.Number = i
    End Sub
End Class

最后，也许你不需要扩展课程，但你只是想找一种方便的方法来在一行中初始化它：

Dim foo = New Foo("test") With {.Number = 4711}

如何在VB.Net中扩展类的构造函数？

1 个答案: