Mastering PowerBuilder

Extending PFC

One of the most important decisions on a PFC project involves the selection of the extension method and must be made on the very first PFC based project. The extension methods must be selected with care and the choices made are not easily reversed. As is the case with any class library, one of the first questions is: "Where do I place the code?". Finding the right event provides half the answer. You have to determine whether the additional logic belongs in the extension layer.

There are three choices available to us.

• Change objects in PFE directly and use them
• Add another layer by inheriting from PFE
• Insert another layer between PFC and PFE