Simple Generic Upcast example in vb.net using reflection

Posted by Michael Doyon / on 2/23/2010 01:43:00 PM / /

Here is a quick example of how one can use reflection to perform an upcast in vb.net. 

In the sample code below, you have  a person class and a contact class.  The contact class inherits from the person class.  Additionally, you have an instance of the Person class which needs to be converted to an instance of the Contact class.  The below code can be used to perform this conversion. 

This may not be the best way to do this, but it is certainly an easy and quick way of performing the task.

1. Module Module1
2.  
3.     Sub Main()
4.         Dim p As New Person() With {.First = "Test", .Last = "User"}
5.         Console.WriteLine("{0} {1} {2}", p.GetType.FullName, p.First, p.Last)
6.  
7.         Dim c As Contact = Upcast(Of Person, Contact)(p)
8.         c.Phone = "555-123-4567"
9.         Console.WriteLine("{0} {1} {2} {3}", c.GetType.FullName, c.First, c.Last, c.Phone)
10.         c.CallContact()
11.  
12.         Console.ReadLine()
13.     End Sub
14.  
15.     Public Function Upcast(Of B, S As {New, B})(ByVal baseObj As B) As S
16.         Dim superObj As S = New S()
17.         Dim superProp As System.Reflection.PropertyInfo = Nothing
18.  
19.         For Each baseProp As System.Reflection.PropertyInfo In baseObj.GetType().GetProperties()
20.             superProp = superObj.GetType().GetProperty(baseProp.Name)
21.             superProp.SetValue(superObj, baseProp.GetValue(baseObj, Nothing), Nothing)
22.         Next
23.  
24.         Return superObj
25.     End Function
26.  
27.     Public Class Person
28.         Private _First As String
29.         Private _Last As String
30.  
31.         Public Property First() As String
32.             Get
33.                 Return _First
34.             End Get
35.             Set(ByVal value As String)
36.                 _First = value
37.             End Set
38.         End Property
39.  
40.         Public Property Last() As String
41.             Get
42.                 Return _Last
43.             End Get
44.             Set(ByVal value As String)
45.                 _Last = value
46.             End Set
47.         End Property
48.     End Class
49.  
50.     Public Class Contact
51.         Inherits Person
52.  
53.         Private _Phone As String
54.         Public Property Phone() As String
55.             Get
56.                 Return _Phone
57.             End Get
58.             Set(ByVal value As String)
59.                 _Phone = value
60.             End Set
61.         End Property
62.  
63.         Public Sub CallContact()
64.             Console.WriteLine("Calling {0}....", Phone)
65.         End Sub
66.     End Class
67. End Module