VFP Design Pattern Catalog

(Updated: 2005.12.21 03:31:15 PM)

Edit -Find- Recent Changes Categories Road Map [A-F] [G-P] [Q-Z] New Topic Home

A place to list documented VFP examples of Design Patterns

Attention 3rd Party Vendors -
Before we had a lot of published resources for making use of Design Patterns to solve problems in VFP, many of us learned how to recognize a particular pattern by studying your products & tools. Those examples are just as important as a published work IMHO, so please feel free to note your examples on the following list or elsewhere in the wiki!

Abstract Factory

CodeBook and related framework documentation

Abstract Factory Code Sample by Kevin McNeish on Microsoft's VFP site. Fixed dead link - works now.

Fox Talk article 3/2002, The Kit Box: As a Matter of Fact�ory by Andy Kramek and Marcia Akins

Subscribers only.
Adapter Pattern

Fox Talk article 7/1/99, Best Practices: Seeing Patterns: The Adapter by Jefferey Donnici

Fox Talk article 9/1/02 What's in a name?
This month, Andy Kramek and Marcia Akins dive into the world of design patterns trying to solve a puzzling naming mystery. According to Design Patterns (Gamma, Helm, Johnson, and Vlissides, Addison Wesley, 1995), the name "Wrapper" is a synonym for both the "Adapter" and the "Decorator" patterns. However, because these are quite clearly different patterns, logically they can't both be called "Wrapper."

AggregatePattern

FoxPro Advisor June 2004 Discover the Advantages of OOP Over Procedural Programming by Mike Yearwood
Bridge Pattern

Bridge Design Pattern Paper by Steven Black

Fox Talk article 3/1/96, Extend and Adapt Your Classes with Bridges by Steven Black

FoxPro Advisor March 1998 article Use Patterns to Increase Reuse and Flexibility by YAlan Griver

Introduction to Design Patterns by YAlan Griver - Broken Link!

Fox Talk article 11/1/98, Best Practices: Seeing Patterns: The Bridge by Jefferey Donnici

Simple Code Example

ox = createobject('Abstraction')
? ox.DoSomething()

define class Abstraction as custom
   oImp = .null.
   function init
      this.oImp = createobject("Implementor")
   function destroy
      this.oImp = .null.
   function DoSomething
      return this.oImp.dosomething()
enddefine

define class Implementor as custom
   function DoSomething()
      return "Something is done by the implementor."
enddefine

Chain Of Responsibility

Fox Talk article 4/1/99, ~~Best Practices: Seeing Patterns: Chain of Responsibility~~ by Jefferey Donnici

Fox Talk article 01/98, discussing Chain Of Responsibility design pattern in an error handling scheme, Reusable Tools: Error Handling Revisited by Doug Hennig. Also available from the Technical Papers page of the Stonefield Systems Group Web site.

FoxPro Advisor December 2001, Chain of Responsibility, by Rick Hodder

Fox Talk article 10/04: Parsing Power Tools, Part 4 by Lauren Clarke and Randy Pearson. Excellent non-hierarchical example of Chain Of Responsibility pattern.
CommandPattern

Fox Talk article 10/1/99, Best Practices: Seeing Patterns: The Command by Jefferey Donnici
CompositePattern

Fox Talk article 12/1/99, Best Practices: Seeing Patterns: The Composite by Jefferey Donnici

FoxPro Advisor January 2002, Composite Pattern by Rick Hodder
Decorator Pattern

Decorator Design Pattern Paper by Steven Black

Introduction to Design Patterns by YAlan Griver - Broken Link!

Fox Talk article 7/1/96, Design Patterns: Wrappers by Steven Black

FoxPro Advisor article 5/98, Enhance Existing Code with the Decorator by YAlan Griver

Decorator Pattern topic now includes another fine example from Steven Black

DecoratingWithTHIS_ACCESS, and Decorating for the Busy Developer by Lauren Clarke
ElementPattern

FoxPro Advisor June 2004 Discover the Advantages of OOP Over Procedural Programming by Mike Yearwood. While technically this may not be a pattern, by having an element class, I made it easier to work with the elements in the aggregate.
FactoryMethodPattern

Fox Talk article 01/01/2000, Best Practices: Seeing Patterns: The Factory Method by Jefferey Donnici

Working link!

Hook Operation

Hook Operations Design Pattern Paper by Steven Black
IteratorPattern

Fox Talk article 6/1/99, Best Practices: Seeing Patterns: The Iterator by Jefferey Donnici

FoxPro Advisor October 2001 The Iterator Pattern Makes Coding Easier by Rick Hodder

Iterator Pattern From Text by Joe Kuhn

FoxPro Advisor June 2004 Discover the Advantages of OOP Over Procedural Programming by Mike Yearwood
Layers

Design Pattern: Layers, by Steven Black
MediatorPattern

Mediator Design Pattern Paper by Steven Black

Introduction to Design Patterns by YAlan Griver - Broken Link!

Fox Talk Article 12/1/98, Best Practices: Seeing Patterns: The Mediator by Jefferey Donnici

see also PushMediator for active mediators, and PullMediator or Passive Mediator Pattern