Adobe® Flex® 4 Language Reference
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__Global__ 
Namespace 
PackageTop Level
Classpublic final class Namespace
InheritanceNamespace Inheritance Object

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9, Flash Lite 4

The Namespace class contains methods and properties for defining and working with namespaces. There are three scenarios for using namespaces:
  • Namespaces of XML objects Namespaces associate a namespace prefix with a Uniform Resource Identifier (URI) that identifies the namespace. The prefix is a string used to reference the namespace within an XML object. If the prefix is undefined, when the XML is converted to a string, a prefix is automatically generated.
  • Namespace to differentiate methods Namespaces can differentiate methods with the same name to perform different tasks. If two methods have the same name but separate namespaces, they can perform different tasks.
  • Namespaces for access control Namespaces can be used to control access to a group of properties and methods in a class. If you place the properties and methods into a private namespace, they are inaccessible to any code that does not have access to that namespace. You can grant access to the group of properties and methods by passing the namespace to other classes, methods or functions.

This class shows two forms of the constructor method because each form accepts different parameters.

This class (along with the XML, XMLList, and QName classes) implements powerful XML-handling standards defined in ECMAScript for XML (E4X) specification (ECMA-357 edition 2).

View the examples

See also



Public Properties
 PropertyDefined By
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
  prefix : String
The prefix of the namespace.
Namespace
 Inheritedprototype : Object
[static] A reference to the prototype object of a class or function object.
Object
  uri : String
The Uniform Resource Identifier (URI) of the namespace.
Namespace
Public Methods
 MethodDefined By
  
Namespace(prefixValue:*, uriValue:*)
Creates a Namespace object according to the values of the prefixValue and uriValue parameters.
Namespace
  
Namespace(uriValue:*)
Creates a Namespace object.
Namespace
 Inherited
Indicates whether an object has a specified property defined.
Object
 Inherited
Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.
Object
 Inherited
Indicates whether the specified property exists and is enumerable.
Object
 Inherited
Sets the availability of a dynamic property for loop operations.
Object
 Inherited
Returns the string representation of this object, formatted according to locale-specific conventions.
Object
  
Equivalent to the Namespace.uri property.
Namespace
  
Returns the URI value of the specified object.
Namespace
Property Detail

prefix

property
prefix:String

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9

The prefix of the namespace.



Implementation
    public function get prefix():String
    public function set prefix(value:String):void

uri

property 
uri:String

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9

The Uniform Resource Identifier (URI) of the namespace.



Implementation
    public function get uri():String
    public function set uri(value:String):void
Constructor Detail

Namespace

()Constructor
public function Namespace(prefixValue:*, uriValue:*)

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9

Creates a Namespace object according to the values of the prefixValue and uriValue parameters. This constructor requires both parameters.

The value of the prefixValue parameter is assigned to the prefix property as follows:

  • If undefined is passed, prefix is set to undefined.
  • If the value is a valid XML name, as determined by the isXMLName() function, it is converted to a string and assigned to the prefix property.
  • If the value is not a valid XML name, the prefix property is set to undefined.

The value of the uriValue parameter is assigned to the uri property as follows:

  • If a QName object is passed, the uri property is set to the value of the QName object's uri property.
  • Otherwise, the uriValue parameter is converted to a string and assigned to the uri property.

Note: This class shows two constructor method entries because each form accepts different parameters. The constructor behaves differently depending on the type and number of arguments passed, as detailed in each entry. ActionSript 3.0 does not support method or constructor overloading.

Parameters
prefixValue:* — The prefix to use for the namespace.
 
uriValue:* — The Uniform Resource Identifier (URI) of the namespace.

Namespace

()Constructor 
public function Namespace(uriValue:*)

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9

Creates a Namespace object. The values assigned to the uri and prefix properties of the new Namespace object depend on the type of value passed for the uriValue parameter:

  • If no value is passed, the prefix and uri properties are set to an empty string.
  • If the value is a Namespace object, a copy of the object is created.
  • If the value is a QName object, the uri property is set to the uri property of the QName object.

Note: This class shows two constructor entries because each form accepts different parameters. The constructor behaves differently depending on the type and number of parameters passed, as detailed in each entry. ActionSript 3.0 does not support method or constructor overloading.

Parameters
uriValue:* — The Uniform Resource Identifier (URI) of the namespace.
Method Detail

toString

()method
AS3 function toString():String

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9

Equivalent to the Namespace.uri property.

Returns
String — The Uniform Resource Identifier (URI) of the namespace, as a string.

valueOf

()method 
AS3 function valueOf():String

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0 Flash Player 9

Returns the URI value of the specified object.

Returns
String — The Uniform Resource Identifier (URI) of the namespace, as a string.
NamespaceExample.as

The following example shows how to work with namespaces defined in XML objects. This is accomplished with the following steps:
  1. The example defines three Namespace objects, each with a unique URI that defines a namespace.
  2. The example defines an XML variable named myXML and assigns it to the return value of getRSS(). The getRSS() method defines an XML object that contains several namespaces and returns that XML object.
  3. The example declares and evaluates an Array variable by calling the parseRSS() method with myXML passed to it. In parseRSS(), the default XML namespace is defined as rss and the example defines an XMLList variable by assigning the list of item objects in myXML. An array is created and populated with various nodes within myXML.item. The array is then returned.
  4. The elements in the array are printed using a for loop and three calls to trace().
package {
    import flash.display.Sprite;

    public class NamespaceExample extends Sprite {
        private var rss:Namespace = new Namespace("http://purl.org/rss/1.0/");
        private var rdf:Namespace = new Namespace("http://www.w3.org/1999/02/22-rdf-syntax-ns#");
        private var dc:Namespace  = new Namespace("http://purl.org/dc/elements/1.1/");

        public function NamespaceExample() {
            var myXML:XML = getRSS();
            var rssItems:Array = parseRSS(myXML);
            
            var len:uint = rssItems.length;
            for (var i:uint; i < len; i++) {
                trace(rssItems[i].title);
                trace(rssItems[i].creator);
                trace(rssItems[i].date);
                // Adobe Flash Developer Center
                // Adobe
                // 2005-08-08
                // Flex Developer Center
                // Adobe
                // 2005-10-16                
            }
        }
        
        private function parseRSS(rssXML:XML):Array {
            default xml namespace = rss;

            var items:XMLList = rssXML.item;

            var arr:Array = new Array();            
            var len:uint = items.length();
            for (var i:uint; i < len; i++) {
                arr.push({title:items[i].title, creator:items[i].dc::creator, date:items[i].dc::date});
            }
            
            return arr;
        }

        private function getRSS():XML {
            var myXML:XML =  <rdf:RDF
              xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
              xmlns="http://purl.org/rss/1.0/"
              xmlns:dc="http://purl.org/dc/elements/1.1/"
            >
              <channel rdf:about="http://www.xml.com/cs/xml/query/q/19">
                <title>Test RSS</title>
                <link>http://www.adobe.com/</link>
                <description>This is a test RSS document.</description>
                <language>en-us</language>
                <items>
                  <rdf:Seq>
                <rdf:li rdf:resource="http://www.adobe.com/devnet/flash/"/>
                <rdf:li rdf:resource="http://www.adobe.com/devnet/flex/"/>
                  </rdf:Seq>
                </items>
              </channel>
              <item rdf:about="http://www.adobe.com/devnet/flash/">
                <title>Adobe Flash Developer Center</title>
                <link>http://www.adobe.com/devnet/flash/</link>
                <description>Welcome to the Flash Developer Center</description>
                <dc:creator>Adobe</dc:creator>
                <dc:date>2005-08-08</dc:date>    
              </item>
              <item rdf:about="http://www.adobe.com/devnet/flex/">
                <title>Flex Developer Center</title>
                <link>http://www.adobe.com/devnet/flex/</link>
                <description>Welcome to the Flex Developer Center</description>
                <dc:creator>Adobe</dc:creator>
                <dc:date>2005-10-16</dc:date>    
              </item>
            </rdf:RDF>;
            
            return myXML;
        }
    }
}
Namespace_2_Example.as

The following example shows how namespaces can be used to differentiate methods that have the same name but perform different tasks. In this example, three methods named hello() reside in separate namespaces; each returns a different string when called.
package {

    import flash.display.Sprite;

    public class Namespace_2_Example extends Sprite {    
        public function Namespace_2_Example() {
            var vocab:MultilingualVocabulary = new MultilingualVocabulary();

            trace(vocab.hello());    // hello
            
            var languages:Array = vocab.getLanguages();
            
            for (var i:uint; i < languages.length; i++) {
                var ns:Namespace = languages[i];
                if (ns != null) {
                    trace(ns.toString() + ": " + vocab.ns::hello());
                    // hello
                    // MultilingualVocabulary:Hawaiian: aloha
                    // MultilingualVocabulary:French: bon jour
                }
            }
        }
    }    
}

class MultilingualVocabulary {
    public namespace French;
    public namespace Hawaiian;
    private var languages:Array;

    public function MultilingualVocabulary() {
        languages = new Array(Hawaiian, French);
    }
        
    public function hello():String { 
        return "hello";
    }

    Hawaiian function hello():String {
        return "aloha";
    }

    French function hello():String { 
        return "bon jour";
    }
        
    public function getLanguages():Array {
        return languages;
    }
}
Namespace_3_Example.as

The following example uses namespace names to select an appropriate variable value. It shows how you can store a namespace value in a variable and use that variable to refer to objects within that namespace.

The example defines namespaces and colors that correspond to mouse states for a rectangular button. Each time the button is drawn, the example applies the appropriate color (out is red; over is yellow; down is white) by referencing the bgcolor variable for the corresponding namespace (out, over, down).

package {
    import flash.display.Sprite;
  
    public class Namespace_3_Example extends Sprite {     
        public function Namespace_3_Example() {
            addChild(new StateButton("Press Me."));
        }
    }
}

import flash.display.Sprite;
import flash.text.TextField;
import flash.events.Event;
import flash.events.MouseEvent;

class StateButton extends Sprite{
    private namespace out;
    private namespace over;
    private namespace down;
    private var label:TextField;
    private var labelTxt:String;
    private var ns:Namespace;
    out var bgColor:Number = 0xFF0000;
    over var bgColor:Number = 0xFFFF00;
    down var bgColor:Number = 0xFFFFFF;
      
    public function StateButton(str:String) {
        buttonMode = true;
        labelTxt = str;
        ns = out;
        draw();
        addLabel();
        addListeners();
    }

    private function addLabel():void {
        label = new TextField();
        label.text = labelTxt;
        label.width = 50;
        label.height = 20;
        label.mouseEnabled = false;
        addChild(label);
    }
      
    private function addListeners():void {
        addEventListener(MouseEvent.MOUSE_UP, mouseOverHandler);
        addEventListener(MouseEvent.MOUSE_OUT, mouseOutHandler);
        addEventListener(MouseEvent.MOUSE_OVER, mouseOverHandler);
        addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);
    }
 
    private function mouseOutHandler(e:Event):void {
        ns = out;
        draw();
    }
 
    private function mouseOverHandler(e:Event):void {
        ns = over;
        draw();
    }
 
    private function mouseDownHandler(e:Event):void {
        ns = down;
        draw();
    }
 
    private function draw():void {
        this.graphics.clear();
        this.graphics.beginFill(ns::bgColor);
        this.graphics.drawRect(0, 0, 60, 20);
    }
}