Release 10.1A: OpenEdge Development:
ADM and SmartObjects

Defining dynamic SmartLinks

Sometimes a SmartObject application requires a link that passes messages between SmartObjects more dynamically; that is, the particular message to be passed (and any resulting processing) is determined by an application user’s run-time choice. This type of link is a dynamic SmartLink.

When you define a dynamic SmartLink, you do not need to provide the support structure for standard events required for static SmartLinks (see the previous section for details). If, at design time, you define between two SmartObjects a SmartLink not in the SupportedLinks list for either object, the addLink procedure registers the link as a subscription to an event of the same name as the links. (You also can do this programmatically, by running addLink in application code.)

The following example illustrates how to define a dynamic SmartLink. This SmartLink, called ProcessCalc, links a simple SmartObject and a SmartDataObject, passing messages that invoke processing in the SmartDataObject. The particular message sent, and the processing invoked, are determined at run time by the choice of the application user.

To define the ProcessCalc dynamic SmartLink, in the AppBuilder:

Create a SmartDataObject that contains an internal procedure named ProcessCalc that has the following code:

DEFINE INPUT PARAMETER pcCalcType AS CHARACTER NO-UNDO. CASE pcCalcType: WHEN "Totals":U THEN RUN calcTotals. WHEN "Discounts":U THEN RUN calcDiscounts. END CASE.

Create the code for the calcTotals and calcDiscounts procedures.
Create a simple SmartObject called sCalcPanel.w that contains two buttons named Calculate Totals and Calculate Discounts, and add the following trigger code to these buttons:

ON CHOOSE OF btnCalcTotals DO: PUBLISH "ProcessCalc":U (INPUT "Totals":U). END. ON CHOOSE OF btnCalcDiscounts DO: PUBLISH "ProcessCalc":U (INPUT "Discounts":U). END.

Create a SmartWindow.
Drop the SmartDataObject onto the SmartWindow.
Drop the sCalcPanel.w simple SmartObject onto the SmartWindow.
Add a SmartLink as follows:
Invoke the Link Advisor.
Choose Add. The Add a SmartLink dialog box appears.
Choose h_sCalcPanel as the source.
Choose New... as the Link Type.
Enter ProcessCalc as the New Link Type.
Choose the SmartDataObject as the target.
Click OK.

When you run this application:

Choosing the Calculate Totals button invokes ProcessCalc in the SmartDataObject with the Totals input parameter, which runs the calcTotals procedure.
Choosing the Calculate Discounts button invokes ProcessCalc in the SmartDataObject with the Discounts input parameter, which runs the calcDiscounts procedure.

Thus, the ProcessCalc SmartLink is dynamic, in the sense that the link name is not bound to a set of event procedure names that are statically defined in the SmartObjects.