About user objects

There are two major types of user objects: visual and class.

A visual user object is a reusable control or set of controls that has a certain behavior. There are three types—standard, custom, and external.

**Table 5-1: Visual user object types**
Visual user objects	Description
Standard	Inherited from a specific visual control. You can set properties and write scripts so that the control is ready for use. It has the same events and properties as the control it is inherited from plus any that you add.
Custom	Inherited from the UserObject system class. You can include many controls in the user object and write scripts for their events. Each control in the user object has the same events and properties as the controls from which they are inherited plus any that you add.
External	A user object that displays a visual control defined in a DLL. The control is not part of the PowerBuilder object hierarchy. The DLL developer provides information for setting style bits that control its presentation. Its events, functions, and properties are specified by the developer of the DLL. An external user object is not the same as an OCX, which you can put in an OLE control.

Class user objects consist of properties, functions, and sometimes events. They have no visual component. There are two types—standard and custom.

**Table 5-2: Class user object types**
Class user objects	Description
Standard	Inherits its definition from a nonvisual PowerBuilder object, such as the Transaction or Error object. You can add instance variables and functions. A few nonvisual objects have events—to write scripts for these events, you have to define a class user object.
Custom	An object of your own design for which you define instance variables, events, and functions in order to encapsulate application-specific programming in an object.

For information on defining and using user objects, see the PowerBuilder Users Guide.