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Prevent Derivation◄╣

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Prevent Derivation (VB.Net and ASP Classic Cross Reference Guide)

By Mike Prestwood

VB.Net versus ASP Classic: A side by side comparison between VB.Net and ASP Classic.

OOP Details

More object oriented (OO) stuff.

Prevent Derivation

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How do you prevent another class from inheriting and/or prevent a class from overriding a member.

VB.Net: NotInheritable, NotOverridable

With VB.Net, use the NotInheritable keyword to prevent a class from being inherited from and use the NotOverridable keyword to prevent a method from being overridden.

A method marked NotOverridable must override an ancestor method. If you mark a class NotInheritable, all members are implicitly not overridable so the NotOverridable keyword is not legal.

Syntax Example:

Public Class Machine

  Public Overridable Sub Speak(ByRef pSentence As String)
    MessageBox.Show(pSentence)
  End Sub
End Class

Public Class Robot
  Inherits Machine

  Public NotOverridable Overrides Sub Speak(ByRef pSentence As String)
    MessageBox.Show(pSentence)
  End Sub
End Class

Public NotInheritable Class Cyborg
  Inherits Robot
End Class

ASP Classic: Not Supported