View this PageEdit this PageAttachments to this PageHistory of this PageHomeRecent ChangesSearch the SwikiHelp Guide
Hotspots: Admin Pages | Turn-in Site |
Current Links: Cases Final Project Summer 2007

Discussion 2 (Part I/II) - Nick De Jesus

Discussion 2
Part I

The Portland Form is a simple format of writing and presenting a pattern solution to a problem coined by the three creators, all of whom were from Portland, Oregon. The system patterns of this form place itself and the forces that made it within the context of both stronger and weaker forces. A common algorithm used to examine this would be: Force A created Problem B, so build Object C to fix it. While not a exhaustive or in-depth design apttern, it is basic, easy to use for any audience and methodical. The Portland Form is a, however, best used for people who actually know what they are talking baout, and have a creative slant to their logical thinking.

This is a very simple and practical way of designing a solution to a problem. By using the Portland Form, the designers keep the big picture of the problem in mind, without having to get caught up or confused with minor ambiguous details. The Portland Form is also an elegant way to get the ball rolling for many design solutions, as it provides a logical goal in sight, and gives the designers somewhere to start. Using this method is wise for situations in which critical thinking is only a secondary step, and with its ability to provide the first step towards any problem solving, the Portland Form is a good tool to use to start any design.

Source :
http://c2.com/ppr/about/portland.html

Part II

One design pattern that can be highly used in the OO paradigm is the use of Factory Methods. This pattern takes advantage of the delegation principle key to OO programming, and used to allow subclasses to decided what type of concrete object they need to be for themselves, making it ideal for situations when the application knows WHEN it has to create and object, but not WHAT object in particular. A creational pattern, Factory classes can be viewed as variant interface whose sole function is to create objects based of what the subclasses choose. Since Factory classes have high usages in certain situations in languages such as Java, I feel such a powerful and useful method can be used in Squeak as well. Having made a Factory class once before, Iunderstand how to use one, and its functional advantage. Though I do not know how to implement it in Squeak, where everything is already an object, I imagine the syntax would change dramtically, but the principalwould remain.

Source:
http://gsraj.tripod.com/design/creational/factory/factory.html

Link to this Page