This is my take on creating an Enumerator class in Flex.

AS3 does not support Enumerators so a class with static constants is used as per the Java Enumerator class pattern.

This implementation is type safe and final. It also contains static helper functions; values() which returns an array of the Enumerator objects (useful for iterations) and getByValue() which allows for easy retrieval of a typed Enumerator object from its primitive value.

1.  
2. package
3. {
4. import flash.errors.IllegalOperationError;
5. import flash.utils.Dictionary;
6. import flash.utils.describeType;
7.  
8. /**

9. * Example Enumerator Representing different RGB Colors
10. */
11. public final class ColorEnum
12. {
13. /* PUBLIC */
14.  
15. public static var RED:ColorEnum = new ColorEnum('RED', PrivateEnforcer);
16. public static var GREEN:ColorEnum = new ColorEnum('GREEN', PrivateEnforcer);
17. public static var BLUE:ColorEnum = new ColorEnum('BLUE', PrivateEnforcer);
18.  
19.  
20. /**

21. * Constructor
22. */
23. public function ColorEnum(value:String, privateEnforcer:Class)
24. {
25. // Force private call only
26. if (privateEnforcer != PrivateEnforcer)
27. {
28. throw new IllegalOperationError("Invalid constructor access");
29. }
30.  
31. // Add Enum value
32. this._value = value;
33. }
34.  
35.  
36. /**

37. * Get all Enumerator Values
38. */
39. public static function values():Array
40. {
41. /* LOCALS */
42. var values:Array = new Array();
43. var value:ColorEnum = null;
44.  
45. if (ColorEnum._values == null)
46. ColorEnum.buildValues();
47.  
48. for each (value in ColorEnum._values)
49. values.push(value);
50.  
51. return values;
52. }
53.  
54.  
55. /**

56. * Get an Enumerator instance by its primative value
57. */
58. public static function getByValue(value:String):ColorEnum
59. {
60. if (ColorEnum._values == null)
61. ColorEnum.buildValues();
62.  
63. return ColorEnum._values[value] as ColorEnum;
64. }
65.  
66.  
67. /**

68. * override value
69. */
70. public function valueOf():Object
71. {
72. return this._value;
73. }
74.  
75.  
76. /**

77. * override toString
78. */
79. public function toString():String
80. {
81. return this._value;
82. }
83.  
84.  
85.  
86. /* PRIVATE */
87.  
88. private var _value:String = '';
89.  
90. private static var _values:Dictionary = null;
91.  
92.  
93. /**

94. * Build static dictionary of all Enum consts and values
95. */
96. private static function buildValues():void
97. {
98. /* LOCALS */
99. var metaData:XML = describeType(VehicleTypeEnum);
100. var node:XML = null;
101.  
102. // Create values Dictionary
103. ColorEnum._values = new Dictionary();
104.  
105. // Add Each Enum const and value
106. for each (node in metaData.children())
107. {
108. if (node.name() == 'variable' && node.@type == metaData.@name)
109. ColorEnum._values[ColorEnum[node.@name].toString()] = ColorEnum[node.@name];
110. }
111.  
112. }
113. }
114. }
115.  
116. class PrivateEnforcer {}
117. Download this code: ColorEnum.as.txt

This entry was posted on Monday, January 25th, 2010 at 7:24 pm and is filed under Flex. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.