Release 10.1A: OpenEdge Development:
Progress 4GL Reference

> ## Handle Reference

> This chapter describes Progress object handles and lists the attributes and methods of each one. Object handles are essentially addresses that provide access to 4GL objects in memory. These objects include widgets, which encapsulate user interface capabilities, and other object types that provide access to a variety of OpenEdge session capabilities.

> Progress makes object handles available in two ways:

> - Directly, as system handle values. A system handle is a Progress keyword that evaluates to an object handle whose object type is implied by the keyword. For example, the CURRENT-WINDOW system handle is a handle to a window widget. To access the attributes and methods of a system handle, you can use the keyword directly, or you can assign the keyword value to a handle variable and use the variable to reference the attributes and methods:

>     DEFINE hHandle AS HANDLE NO-UNDO.
>     hHandle = THIS-PROCEDURE. /* Set a handle to a procedure object. */
>     DISPLAY THIS-PROCEDURE:GET-SIGNATURE(). /* Displays the same */
>     DISPLAY hHandle:GET-SIGNATURE(). /* signature as this statment. */

> - Indirectly, as values output from certain Progress statements, including other handle attributes and methods. You can access the attributes and methods of any object by assigning its handle to a handle variable, which can hold handle values of any type. You can then use this variable to reference the attributes and methods of the object:

>     DEFINE hHandle AS HANDLE NO-UNDO.
>     CREATE SERVER hHandle. /* Create a handle to a server object. */
>     hHandle:CONNECT().     /* Execute a server object method. */

> The following reference entries include both system handles and handle types for objects not necessarily referenced using system handles. Each system handle is listed by its keyword (all upper case, for example: SESSION system handle), and each handle type is listed by its type (upper/lower case, for example: Server object handle).

> Each entry lists the attributes and methods supported by the handle or refers you to a more general entry with the same list. For example, the attributes and methods of the CURRENT-WINDOW system handle appear under the WINDOW widget entry. Widgets, in general, share a common set of user interface capabilities. For a list of the attributes and methods supported by each widget, see the "Widget Reference" section.

> For more information on how to access attributes and methods using all object handles, see the "Attributes and Methods Reference" section, which includes a complete reference entry for each attribute and method.

> Note: You may consider an object handle to be supported for all interfaces, on all operating systems, and for SpeedScript unless otherwise indicated in the reference entry.

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