The Message object
The Message object is a predefined PowerBuilder global object
(like the default Transaction object SQLCA and the Error object)
that is used in scripts to process Microsoft Windows events that
are not PowerBuilder-defined events.
When a Microsoft Windows event occurs that is not a PowerBuilder-defined event, PowerBuilder populates
the Message object with information about the event.
Other uses of the Message object
The Message object is also used:
- To communicate parameters between windows when you
open and close them
For more information, see the descriptions
of OpenWithParm, OpenSheetWithParm,
and CloseWithReturn in the PowerScript
Reference
. - To pass information to an event if optional parameters
were used in TriggerEvent or PostEvent
For more information, see the PowerScript
Reference
.
Customizing the Message object
You can customize the global Message object used in your application
by defining a standard class user object inherited from the built-in
Message object. In the user object, you can add additional properties
(instance variables) and functions. You then populate the user-defined
properties and call the functions as needed in your application.
For more information about defining standard
class user objects, see the PowerBuilder User’s
Guide
.
Message object properties
The first four properties of the Message object correspond
to the first four properties of the Microsoft Windows message structure.
| Property | Datatype | Use |
|---|---|---|
| Handle | Integer | The handle of the window or control. |
| Number | Integer | The number that identifies the event (this number comes from Windows). |
| WordParm | UnsignedInt | The word parameter for the event (this parameter comes from Windows). The parameter’s value and meaning are determined by the event. |
| LongParm | Long | The long parameter for the event (this number comes from Windows). The parameter’s value and meaning are determined by the event. |
| DoubleParm | Double | A numeric or numeric variable. |
| StringParm | String | A string or string variable. |
| PowerObjectParm | PowerObject | Any PowerBuilder object type including structures. |
| Processed | Boolean | A boolean value set in the script for the user-defined event:
|
| ReturnValue | Long | The value you want returned to Windows when Message.Processed is TRUE. When Message.Processed is FALSE, this attribute |
Use the values in the Message object in the event script that
caused the Message object to be populated. For example, suppose
the FileExists event contains the following script. OpenWithParm displays
a response window that asks the user if it is OK to overwrite the
file. The return value from FileExists determines
whether the file is saved:
|
1 |
OpenWithParm( w_question, &<br /> "The specified file already exists. " + &<br /> "Do you want to overwrite it?" )<br />IF Message.StringParm = "Yes" THEN<br /> RETURN 0 // File is saved<br />ELSE<br /> RETURN -1 // Saving is canceled<br />END IF |
For information on Microsoft message numbers
and parameters, see the Microsoft Software Developer’s
Kit (SDK) documentation.