Enumerating data types in Actionscript 3 (AS3)
In computer programming, an enumerated type is an abstract data type used to model an attribute that has a specific number of options (or identifiers) such as the suit of a playing card (i.e. a Club, Diamond, Heart or Spade). Using this type allows the program to handle the attribute more efficiently than a string while maintaining the readability of the source code.
-from Wikipedia
I've found this method (illustrated in code below) for enumeration of datasets to be useful, and at this point even essential, in my applications. Prior to this I was actually cutting and pasting the arrays that I was using in my various combo boxes and other selection components as dataProviders. By breaking the dataset into an enumeration class, it makes it easy to maintain the list and lets the dataset function as a first class citizen, ensuring that your data is consistent throughout the application.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 | package enum { /** * CloudTypeEnum enumerates cloud types. * @author JHooks * */ public class CloudTypeEnum { public static const NONE:CloudTypeEnum = new CloudTypeEnum( "None", -1 ); public static const CUMULUS:CloudTypeEnum = new CloudTypeEnum( "Cumulus", 0 ); public static const STRATUS:CloudTypeEnum = new CloudTypeEnum( "Stratus", 1 ); public static const CIRRUS:CloudTypeEnum = new CloudTypeEnum( "Cirrus", 2 ); public static const NIMBUS:CloudTypeEnum = new CloudTypeEnum( "Nimbus", 3 ); public var value:String public var ordinal:int /** * CloudTypeEnum constructor * @param value * @param ordinal * */ public function CloudTypeEnum( value:String, ordinal:int ) { this.value = value; this.ordinal = ordinal; } /** * A list of cloud types * @return * */ public static function get list( ):Array { return [ CUMULUS, STRATUS, CIRRUS, NIMBUS ]; } /** * A list of cloud types appropriate for use in ComboBox and other * selection components as a DataProvider * * myComboBox.dataProvider = CloudTypeEnum.cList; * @return * */ public static function get cList( ):Array { return list.unshift( NONE ); } /** * Select a cloud type by its value property * @param value * @return * */ public static function selectByValue( value:String ):TaskTypeEnum { for each ( var cloudType:TaskTypeEnum in CloudTypeEnum.list ) { if ( value == cloudType.value ) return cloudType; } return NONE; } } } |
Thanks to Cliff Hall who showed this to me via one of his PureMVC demo applications. For the life of me I can't remember which one.
Perfecting OO's Small Classes and Short Methods
This is here as sort of a TODO for myself this year. I want to try this experiment. I really like the concept of breaking down OO projects into this extra fine granularity.
He suggests writing a 1000-line program with the constraints listed below. These constraints are intended to be excessively restrictive, so as to force developers out of the procedural groove. I guarantee if you apply this technique, their code will move markedly towards object orientation. The restrictions (which should be mercilessly enforced in this exercise) are:
1. Use only one level of indentation per method. If you need more than one level, you need to create a second method and call it from the first. This is one of the most important constraints in the exercise.
2. Don’t use the ‘else’ keyword. Test for a condition with an if-statement and exit the routine if it’s not met. This prevents if-else chaining; and every routine does just one thing. You’re getting the idea.
3. Wrap all primitives and strings. This directly addresses “primitive obsession.” If you want to use an integer, you first have to create a class (even an inner class) to identify it’s true role. So zip codes are an object not an integer, for example. This makes for far clearer and more testable code.
4. Use only one dot per line. This step prevents you from reaching deeply into other objects to get at fields or methods, and thereby conceptually breaking encapsulation.
5. Don’t abbreviate names. This constraint avoids the procedural verbosity that is created by certain forms of redundancy—if you have to type the full name of a method or variable, you’re likely to spend more time thinking about its name. And you’ll avoid having objects called Order with methods entitled shipOrder(). Instead, your code will have more calls such as Order.ship().
6. Keep entities small. This means no more than 50 lines per class and no more than 10 classes per package. The 50 lines per class constraint is crucial. Not only does it force concision and keep classes focused, but it means most classes can fit on a single screen in any editor/IDE.
7. Don’t use any classes with more than two instance variables. This is perhaps the hardest constraint. Bay’s point is that with more than two instance variables, there is almost certainly a reason to subgroup some variables into a separate class.
8. Use first-class collections. In other words, any class that contains a collection should contain no other member variables. The idea is an extension of primitive obsession. If you need a class that’s a subsumes the collection, then write it that way.
9. Don’t use setters, getters, or properties. This is a radical approach to enforcing encapsulation. It also requires implementation of dependency injection approaches and adherence to the maxim “tell, don’t ask.”
I went ahead and ordered the ThoughtWorks book too. I've used their Mingle product, which I find very compelling, so I am looking forward to their essays.
Continuous scrolling image thumbnail component for Flex.
Here is the beginnings of a full featured open-source continuous scroll thumbnail component for Flex. It is rough right now, but I plan to polish it and make it something useful. This format is really appealing, as it gives the user a seamless view of a gallery, without any jumps or aggravating scroll bars. Up until now I have been using H and V Lists in flex for my thumbnailing, but they are ugly and don't provide as rich of an experience.
The Scroll Panel from AFComponents was my first choice. It is a very nice component, well priced, and would be just what I need, if not for the fact that my project is open-source and using a commercial component sorta kills the whole thing. After scouring the internet I finally stumbled upon the work Peter Wright has put in on a perpetual scrolling list.
I've modified it to accept an XML list of image objects, as well as perform horizontally. It is also functioning as a slideshow, and I want to allow it to go either H or V depending on the need. It should shape up to be a nice reusable component. Much thanks to Peter for supplying the code to get me started.
Using the Senocular AS3 TransformTool in Flex
Hey,I am so interested about that you had ever used the ‘TransformTool’ library in your Flex project. But there is little examples showing how to use it in flex, Would you please share some example about how to use ‘TransformTool’ in Flex? I have tried as such a way:
but it failed at line
canvas.addChild(defaultTool);
Can you give any hints? Thanks.
Like most pure AS3 display classes, the TransformTool needs to be added to a UIComponent wrapper to function properly in Flex.
