Deriving a New Method from an Existing One

To derive a new method from an existing method, you can use the derived keyword followed by the scope resolution operator (::).

Use the following syntax:
new method : existing method

The following example defines a GetCaption method for WPFNewTextBox that prints the string Caption as is before calling the built-in GetCaption method (defined in the AnyWin class) and printing its return value:

winclass WPFNewTextBox : WPFTextBox
GetCaption () 
Print ("Caption as is: ")
Print (derived::GetCaption ())