Terminology
The class information includes information about the relationships
between objects. These definitions will help you understand what
the information means.
object instance
A realization of an object. The instance exists in memory
and has values assigned to its properties and variables. Object
instances exist only when you run an application.
class
A definition of an object, containing the source code for
creating an object instance. When you use PowerBuilder painters
and save an object in a PBL, you
are creating class definitions for objects. When you run your application, the
class is the datatype of object instances based on that class. In PowerBuilder,
the term object usually refers to an instance
of the object. It sometimes refers to an object’s class.
system class
A class defined by PowerBuilder. An object you define in a
painter is a descendant of a system class, even when you do not
explicitly choose to use inheritance for the object you define.
parent
The object that contains the current object or is connected
to the object in a way other than inheritance. This table lists
classes of objects and the classes that can be the parents of those
objects:
|
Object |
Parent |
|---|---|
|
Window |
The window that opened the window. A window might not have a parent. The parent is determined |
|
Menu item |
The menu item on the prior level in the The item on the menu bar is the parent of all the items on |
|
Control on a window |
The window. |
|
Control on user object |
The user object. |
|
TabPage |
The Tab control in which the TabPage |
|
ListViewItem or TreeViewItem |
The ListView or TreeView control. |
|
Visual user object |
The window or user object on which the |
child
A class that is contained within another parent class. Also
called a nested class. For the types of objects that have a parent
and child relationship, see parent.
ancestor
A class from whose definition another object is inherited.
See also descendant.
descendant
An object that is inherited from another object and that incorporates
the specifics of that object: its properties, functions, events,
and variables. The descendant can use these values or override them
with new definitions. All objects you define in painters and store
in libraries are descendants of PowerBuilder system classes.
inheritance hierarchy
An object and all its ancestors.
collapsed hierarchy
A view of an object class definition that includes information
from all the ancestors in the object’s inheritance tree,
not just items defined at the current level of inheritance.
scalar
A simple datatype that is not an object or an array. For example, Integer, Boolean, Date, Any,
and String.
instance variable and property
Built-in properties of PowerBuilder system objects are called
properties, but they are treated as instance variables in the class
definition information.