Every Monday I have to separate out the paper, glass, aluminum, and plastic to recycle and take them up to the curb. This last Monday while engaged in this weekly ritual, I thought that recycling a design pattern might be an interesting exercise. Additionally, it’s the kind of design pattern advantage that can be used at work to save re-inventing the wheel when you have a similar development task. You may remember the Dragon Factory where we employed a Factory Method to set up an easy-to-use drag application. In the original Dragon Factory, both the Creator and Product participants had subclasses. However, with only a slight revision, it’s possible to create a little game for making different faces subclassing only the Product interface (abstract class). Figure 1 shows the File-Class Diagram:
Figure 1: Factory Method with Single Concrete Creator
You can see the design similarities between this application (MrFace) and the Dragon application. The main difference is that this one has a single concrete factory (FaceCreator) for all of the concrete products. The factory churns out all of the Product children and puts them into an array. The Client requests the array from the Creator and pulls out the elements with a loop. As you can see, they’re all draggable elements. Try out the embedded SWF file below to see how it works:
The same Product (from the Dragon application) is re-used so it is unnecessary to revise it. However, instead of a video and a dynamically generated graphic, all of the graphics were put into the Library as Sprite classes. (To make a Sprite class just change the Base class to flash.display.Sprite.) Continue reading ‘ActionScript 3.0 Design Pattern Re-use and Modification’
You will remember the initial query that launched this two-part post started with an inquiry into the possibility of dragging a Video while it was playing. In order to make the query more relevant to design patterns, this second part looks at the process for expanding the larger issue of dragging objects inside a Sprite. Whenever undertaking such a project, begin with the Variation Table (akaMagic Table) to find the possible variations. The wrong way to start developing a design pattern for a practical problem is to look at all of the different class diagrams and pick one that looks like it will fit your problem. Instead, always start by asking, what varies?
In this case, the “hitchhiker” to be dragged is the particular type of object in question. We saw how to drag a Video object, but what about other objects that need to hitchhike on a Sprite to be dragged? So, we’re talking about different objects—or put otherwise—object variation. The closest matching variation in the Magic Table is the variation of the subclass of the object that is instantiated. That means a Factory Method design. (See how easy that was?) Continue reading ‘Hitchhiker’s Guide to ActionScript 3.0: The Dragon Factory—Part 2′
It’s about time for another Golden Lunch Bucket Contest, and once again you can reap fame and fortune! (And again, we’ll provide the former if you provide the latter. This time, though, we must insist that you provide better prizes for yourself if you’re one of the winners!)
If you’re feeling lucky, then enter the contest. Who knows? You might just win, and then you can go nuts! We know, you’ll have to put up with the paparazzi and the inevitable groupies, but that’s just the cost of fame. (Our former winners will give you advice on how to handle it all.) Just remember Dirty Harry’s advice:
You gotta ask yourself one question: Do I feel lucky? Well, do ya, punk?
Gentle Reader, this post includes one completed application and one in the works. The AIR ActionScript 3.0 Design Pattern Catalog is meant to be a developer’s aid, and so your ideas of what to include in the catalog is important. We would really appreciate your comments on what you think would be useful in developing an information template to be used for all of the design patterns.
I recently returned from a trip to Prague in the Czech Republic, and I went to work creating a video player for my HD videos I made using a Flip Mino HD camcorder (http://www.sandlight.net/prague). Rather than pulling out and reusing my trusty State Design Pattern player (see Chapter 10), I decided to start from scratch and create a player not using a design pattern. Then I would take the completed video player and use it as an example to show how to refactor a program to a design pattern. (This will be in an upcoming post.) Since I’ve never had to refactor the original program (tweak, maybe but not refactor), and I hadn’t worked with a State pattern lately, I found myself digging up all of the materials on the State Design Pattern. What I wished I had was a handy desktop app that I could click that would show me the essentials of the different design patterns. It would be an abbreviated design pattern catalog that could be used like the little Design Pattern Principles and Lunch Bucket Rules AIR app. Then when I need a quick reference I could use the desktop app to look up the essentials of the pattern. Continue reading ‘The Developing an AIR ActionScript 3.0 Design Pattern Catalog and the AIR Magic Table’
A few weeks ago we had a survey to see the practices used by professional ActionScript 3.0 developers, and the results are quite interesting. Roughly, 31% of the respondents indicated that they used design patterns and OOP either as a strict policy in developing their products or from within a template. Another 51% indicated that given the time, they’d employ design patterns and all of the good practices, but because of time pressure, often they could not. The smallest category, representing 12% of the respondents, indicated that they didn’t pay attention either to design patterns or good OOP practices. In other words, 88% of the respondents indicated that they were aware of and attempted to use good development practices as a general policy except where it was impossible because of time and/or resource constraints. Continue reading ‘ActionScript 3.0 Design Patterns and OOP At Work: Where Are You?’
It’s about time for another Golden Lunch Bucket Contest, and once again you can reap fame and fortune! (And again, we’ll provide the former if you provide the latter. This time, though, we must insist that you provide better prizes for yourself if you’re one of the winners!)
Bill Sanders
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