Issue Date: FoxTalk March 1996 Extend and Adapt Your Classes with BRIDGEs

This is the first of a series of articles on object-oriented design patterns and how to apply them in Visual FoxPro. The study of design patterns is an exciting new fad; one that produced some of last year's most insightful computer books, a few of which are listed at the end of this article. In the first few articles of this series, I'll present examples of terrific object-orient d design patterns that you can probably use immediately. In the months ahead, I'll occasionally pause on the wider issues of pattern usage and pattern coordination. What is a design pattern? A pattern is a recurring solution to a particular problem. A design pattern is a general, but multifaceted, abstraction of the solution and its applicability. Patterns are found wherever several classes and their instances collaborate as a system. You don't need to "know " about patterns to unconsciously create and use them. Some design patterns, when applied under appropriate conditions to solve the correct sort of problem, have known tendencies to be stable, scaleable, and coherent. These patterns are just now being identified, analyzed, and cataloged. A design pattern defines the parts, collaborations, and responsibilities of classes and instances used in a software subsystem. Thus they abstract the subsystem above the level of classes, instances, and code. Patterns are all about architectures, thei