Oinam's Blog

In general Namespaces allow for group entities like classes, objects and functions under a name. In ActionScript 3.0, Namespaces works like namespaces in an XML. It allows for the control of the visibility of class members.

How to declare Namespace?

namespace ;
@ function @

Example

namespace AddString;
namespace AddNumber;
//
AddString function Sum(a:String,b:String):String
{
return a+b;
}  
//
AddNumber function Sum(a:Number,b:Number):Number
{
return a+b;
}  

How to use Namespace?
Now you can access the Namespace funtions in 2 ways.

1. Using ‘use’ keyword
2. Using fully qualified name (:: notation) 

from the previous example we declared now we can use in 2 ways

// 1.
use AddString
Sum("santosh","kumar");
//
use AddNumber
Sum(1,2);

// 2.
AddString::Sum("santosh","kumar");
AddNumber::Sum(1,2);  

Using NameSpace, we can have same function name defined any number of times. for example function Sum is defined twice for addition of string and as well as for addition of number.

Let us look at the following codes

package
{
	import flash.util.trace;
	import flash.display.Sprite;
	//
	public class Addition extends Sprite
	{
		namespace AddString;
		namespace AddNumber;
		//
		public function Addition()
		{
			trace ( AddString::Sum("Hello","World"));
			trace ( AddNumber::Sum(1,2));
		}
		//
		AddString function Sum(a:String,b:String):String
		{
			return a+b;
		}
		//
		AddNumber function Sum(a:Number,b:Number):Number
		{
			return a+b;
		}  
	}
}

Note

1. If we declare namespace in package we can use same namespace name in multiple classes.

for e.g.

package
{
namespace X
public class A
{
  public function class A()
  {
    X::someMethod()
  }  
  X function someMethod()
  {
  } 
}
//
public class B
{
  public function class B()
  {
    X::someMethod()
  }
  X function someMethod(){
  }
 }
} 

Here, the same Namespace X is used in class A and class B

2. When using Namespaces you cannot specify access modifier like private, public etc

for e.g.

namespace X
// Errror: Access specifiers not allowed in namespace attributes
X private function someMethod()
{
}

3. Namespaces cannot be used like C++ for declaring properties or variables

// Error:
namespace myNamespace
{
int a, b;
}

4. The namespace of superclass can be accessed via subclass using keyword ’super’

super.::

This entry was posted on Tuesday, January 3rd, 2006 at 1:01 am and is filed under Flash. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.