Derived Class and Overrides : Overridable « Class Module « VB.Net Tutorial

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VB.Net Tutorial » Class Module » Overridable 
6.42.4.Derived Class and Overrides
' compile with: vbc PolyExampleVB.vb
Class BaseClass
    Dim As Integer = 5
    Public Overridable Sub Print()
        Console.WriteLine("i is {0}", i)
    End Sub
    Public Overrides Function ToString() As String
        Return i.ToString()
    End Function
End Class
Class DerivedClass
    Inherits BaseClass
    Dim As Double = 2.1
    Public Overrides Sub Print()
        MyBase.Print()
        Console.WriteLine("d is {0}", d)
    End Sub
    Public Overrides Function ToString() As String
        Return MyBase.ToString() " " + d.ToString()
    End Function
End Class
Class TestBaseDerived
    Public Shared Sub Main()
        Dim As New BaseClass()
        Dim As New DerivedClass()
        Dim bd As BaseClass = New DerivedClass() ' note this!
        b.Print()    
        d.Print()
        bd.Print()   
        Console.WriteLine("b: {0}, d: {1}, bd: {2}", b, d, bd)
        Console.ReadLine()
    End Sub
End Class
6.42.Overridable
6.42.1.Overrides Overridable methods
6.42.2.Overrides and Shadows methods from base class
6.42.3.ToString method overrides
6.42.4.Derived Class and Overrides
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