VB6 is considered "object-based" because it supports classes and objects but not inheritance. Inheritance allows a class to get fields and methods from a base class, like this sample in VB.NET:
' Base class Class Dog Public Sub Bark() MessageBox.Show("Woof") End Sub End Class ' Derived class Class BigDog ' Inherit all members from base class Dog Inherits Dog ' Add new member Public Sub EatCat() MessageBox.Show("Munch") End Sub End Class Module App Sub Main() ' Create an instance of the derived class Dim fido As BigDog = New BigDog() ' Call a method from the base class fido.Bark() End Sub End Module
Inheritance is a powerful feature of reuse, allowing you to factor shared functionality between classes into a base class, reusing them in specific derived classes. While there are other new object-oriented features new to VB.NET, inheritance, long present in languages like C++ and Java, is the key new feature in VB.NET that makes it object-oriented instead of object-based.
This was first published in November 2002