Inheritance & Interfaces¶

CrossBasic supports single inheritance and interface implementation, allowing you to build rich type hierarchies.

Inheritance¶

Use the Extends keyword to derive a subclass:

Class Animal
  Sub Speak()
    Print("…")
  End Sub
End Class

Class Dog Extends Animal
  Overrides Sub Speak()
    Print("Woof!")
  End Sub
End Class

Var d As New Dog
d.Speak()  // prints "Woof!"

• Base methods can be overridden with Overrides.
• Call MyBase.MethodName(...) to invoke the parent’s implementation.

Interfaces¶

Define an interface with Interface, then implement it:

Interface IShape
  Sub Draw()
End Interface

Class Circle Implements IShape
  Dim Radius As Double

  Sub Draw() Implements IShape.Draw
    // draw a circle of given Radius
  End Sub
End Class

Var c As New Circle
c.Draw()

• Interfaces declare method signatures.
• Classes implement with Implements InterfaceName.
• Each implementing method must include Implements InterfaceName.MethodName.