Using PowerBuilder extensions
Every PowerBuilder extension requires a compiled C++ shared
library, usually with the extension .pbx (for PowerBuilder
eXtension). The C++ shared
library file contains classes and methods that you use in your PowerScript
target in the same way that you use PowerBuilder system objects
or user objects.
To use the shared library in PowerBuilder, you place it in
PowerBuilder’s search path. In the System Tree, right-click
a library in your PowerScript target, select Import PB Extension
from the pop-up menu, navigate to the shared library, and select
Open. This imports the definitions in the PBX into the library in
your target. You can alternatively add the associated PBD file to
the target’s library search path. The PBD acts as a wrapper
for the C++ shared library, enabling PowerBuilder
to display the objects and methods it contains.
When you deploy an application that uses an extension, the
C++ shared library must be deployed in the application’s
search path with the other PowerBuilder runtime files.
When you import an extension into a PowerScript target, the
classes it contains display in the System Tree as user objects.
You can expand the objects to display properties, events, and functions.
You can inherit from extension objects and use drag-and-drop programming
from the inherited objects in the System Tree as you do for other
user objects.
Using nonvisual classes
In PowerScript, use the classes in a nonvisual extension just
as you would a custom class user object: declare an instance of
the object, use the CREATE statement to create
the instance, invoke the object’s functions, and destroy
the instance when you have finished with it. You can inherit from
the native classes if you want to add functions or events to the
class.
At runtime, instances of the native class are created as normal
PowerBuilder objects.
Using visual classes
You do not need to declare
an instance of a visual class or use the CREATE statement
to create an instance. To use a visual extension, select File>Inherit from
the PowerBuilder menu, select the PBL or PBD that contains the visual class
in the Libraries list in the Inherit from Object dialog box, select
the visual class, and click OK.
In the User Object painter, size the visual object and make
any other changes you need, then save the object. You can then drag
the new user object from the System Tree directly onto a window
or onto another visual control, such as a tab control, and use it
like any other visual user object.
PBXRuntimeError
PowerBuilder extensions can throw a special exception, PBXRuntimeError, that
inherits from the PowerBuilder RuntimeError exception. If you use
an extension in a PowerBuilder application, you should include try-catch
blocks for this exception and report any occurrences to the provider
of the extension. This exception is usually caused by programming
errors within the extension.