To make a global change to the hierarchy you'll need change all the first-level subclasses since the culmination class is read-only, so many of the so-called benefits from using an inheritance hierarchy are largely lost.įigure 1. The problem here is this hierarchy culminates with a read-only class, a Visual FoxPro built-in base class. Major Rule: Use your own classes as the basis for the controls in your applications.įigure 1 illustrates a class hierarchy spawned directly from a VFP base class. That's what this paper is about: how to structure your class libraries so they can scale, at least a little bit.
But to build a 10-meter or 100-meter high tower, you need a plan, and you need to pay attention to process and structure. Like the old saying goes, to build a 1-meter high tower, all you need is a few undamaged beer cans. That's because experience suggests that the complexity of managing Visual FoxPro classes and class libraries varies with the size of the project, the intensity of development activities, the complexity of the project's class design, and on the number of developers involved. Be aware that if you work alone, or if you are working on a small project, what I suggest herein matters much less than if you are developing a larger system, and collaborating with several other developers. I'm writing this document to share some sensible practices for dealing with VFP Class Libraries.
Time permitting, we'll also look at tools to aid in library engineering, documentation, information dissemination, and tactics for version control. we'll also talk about the conceptual and physical management of classes and class libraries, how the VFP Class Browser and Component Gallery play complementary roles in class library management, and how library structures are related to component architecture. this session, for advanced visual foxpro developers, is all about being an effective class librarian, and working smart with visual and code class libraries.
as program size increases, proper structure becomes exponentially more important. Face it: you can't ship a large application without good class management. The more applications you develop, and the bigger the teams that work on them, and the more often the software is revised, the more class library management skills are important.
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