Now we need to create the Document Class that will drive our simple application.  To do that click File>New and select ActionScript File (see Figure 2-1).


Figure 2-1: Create new ActionScript File.

Now we need to save this new AS file in a package.  Packages are a tiddy way to put our Classes into folders.  It is common to create your custom Classes in a directory that is the reverse order of your website or company website name.  My company name is IdentityMine.com so I saved my AS file in a directory called com\identityMine\documentClass\ and named it DocumentClass.as (see Figure 2-2).


Figure 2-2: Save your new AS file in a package or directory structure of com\identityMine\documentClass\DocumentClass.as

Now we need to do something that was introduced in AS3 and that is to create a namespace.  A namespace of an AS file is the same as the package that the AS file is in.  So in our DocumentClass.as file put in the namespace like I did in the code below:

package com.identityMine.documentClass
{
 
}


Now we need to declare the class.  This is the same name as our AS file, see the code below:

package com.identityMine.documentClass
{
 public class DocumentClass extends MovieClip
 {
  
 }
}


In the code above we declared our class as a public class that extends a MovieClip which means it now will inherit all of the properties of a MovieClip.  We need to do this because our DocumentClass is the main Class for our movie.

Something also new to AS3 is that if we want to extend our new DocumentClass to a MovieClip we need to import the Flash MovieClip Class.  I have done this in the code below:

package com.identityMine.documentClass
{
 import flash.display.MovieClip;
 public class DocumentClass extends MovieClip
 {
  
 }
}


Notice that the import statement is above the class declaration.

Now we need to create a Contructor for our DocumentClass.  A contructor is not new to AS3 as AS2 Classes need them as well.  A Constructor is basically a function or method that is called whenever the DocumentClass gets instantiated.  In the case of a Document Class it will get instantiated when our movie first runs.  I have created my constructor in the code below:

package com.identityMine.documentClass
{
 import flash.display.MovieClip;
 public class DocumentClass extends MovieClip
 {
  public function DocumentClass()
  {
   
  }
 }
}


Note: a Contructor must never have a return type such as "void"

Now, lets add a trace statement into our Constructor so we can tell when it is instantiated:

Now let's move onto the next phase and hook our DocumentClass up to our Main.fla