System
object inheritance hierarchy
Contents
Inheritance
One of the most powerful features of PowerBuilder is inheritance. It
enables you to build windows, user objects, and menus that are derived
from existing objects. When you build an object that inherits from another
object, you create a hierarchy (or tree structure) of ancestor and
descendant objects.
Base class object
The object at the top of the hierarchy is a base class object, and
the other objects are descendants of this object. Each descendant inherits
its definition from its ancestor. The base class object typically
implements generalized processing, and each descendant modifies the
inherited processing as needed.
System object hierarchy
The PowerBuilder system objects compose such a hierarchy. At the top
of the hierarchy is the PowerObject, the base class from which all the
objects and controls described in this book descend. The hierarchy also
contains other (generic) base class objects that are not typically used in
application development but are necessary parts of the logical
organization of the hierarchy.