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I'm not a VB.NET defender (I don't like to be labeled so ... en aras de la objetividad!), and I know many different types of programmers (C++, Smalltalk, Java, etc.) who disagree when someone calls VB object-oriented programming (OOP).
However, I read the notes on SearchVB.com's "Polymorphysm Debate." I want to express my humble opinion about the code exposed there: it's only a code design issue, as another member said.
Polymorphysm and inheritance are supported by VB.NET, no doubt; and, in this case, it's only a matter to define a third class named "Child2" where p1() method will be also defined for last (NotOverridable).
Then, in p2() method of Parent Class, taking advantage of the dynamic binding provided by VB.NET, the code will take the Child2 class method p1() (as we used Me.p1())... that's all.
Saludos!
Code:
Module MyModule
Class Parent
Public Overridable Sub p1()
Console.Write("Parent.p1")
End Sub
Public Sub p2()
p1()
End Sub
End Class
Class Child
Inherits Parent
Public Overrides Sub p1()
Console.Write("Child.p1")
p2()
End Sub
End Class
Class Child2
Inherits Parent
NotOverridable Overrides Sub p1()
Console.Write("Child2.p1")
End Sub
End Class
Sub Main()
Dim p As Parent
Dim c As Child
p = New Parent()
p.p1() ' "Parent.p1"
p.p2() ' "Parent.p1"
p = New Child()
p.p1() ' "Child.p1"-"Child2.p1"
p.p2() ' "Child2.p1"
c = New Child()
c.p1()
c.p2()
End Sub
End Module