Comments on: How to use interface in ActionScript 3

By: encoder

encoder — Mon, 28 Nov 2011 12:25:38 +0000

@ yohami by letting you focus on architecture and not the algorithms that actually control the "monster" for example.

By: Daniel

Daniel — Thu, 04 Aug 2011 02:59:58 +0000

For instance

you can use in the interface

function get displayObject():DisplayObject;

in the spriteMount class

public function get displayObject():DisplayObject
{
return this;
}

and in another class

var see:Imonster;

and then

see = new spriteMount();

and then

see.displayObject.x = 100;
see.displayObject.y = 100;

By: steve

steve — Wed, 15 Jun 2011 23:17:54 +0000

I’m building a game with this sort of class hierarchy:

Class Entity extends Sprite
Class Player extends Entity
Class Platform extends Entity
Class Monster extends Entity

These are the main classes, but within class player and class monster I have a reference for a settings object:

Interface EntitySetting
public get…set…
public methods….
abstract methods… (implemented by specific child class)
Class MonsterSetting implements EntitySetting
Class PlayerSetting implements EntitySetting
Class PlatformSetting implements EntitySetting
So in the Specific class settings objects, each using the function headers from the EntitySetting class.

So then I can just have an array of Entity objects in my main game driver class. You can easily perform operations on all objects at once by calling them all Entities, then any specific code will filter through their Settings object. If it is Melee dps monster or a ranged caster monster, or a tall platform, short platform with spikes, w/e.

By: Tim

Tim — Mon, 06 Jun 2011 14:27:06 +0000

@ yohami In addition, this will allow your code to be dynamic down the road. Think of an interface as a way of building functions that can be variable within a class. If you create an interface, then you can create several classes that implement that interface. In this way, those classes define a behavior (functionality) described in the interface. Then you can create an instance of these classes within your main object, and change it over time to basic render all the functions within the interface as 'variable' functions. The short and easy description is that using interfaces allows you to add dynamic behavior (functionality) to your classes, as opposed to hard coding it.

By: max

max — Wed, 19 Jan 2011 01:28:24 +0000

For those struggling about the fact that once an interface is implemented you lose for example the displayobject inheritance (because you cannot extend your interface to a class,) .. the solution is the other way around… you shouldn’t cast to a displayobject but have your object already as displayobject and then eventually cast to your interface when you need specifc stuff from there (isn’t that the meaning of an interface.. ). If I have a base class Page (which may or may not implement an interface) but for sure will extend a displayobject and other subpages like Homepage, Contactpage and so on which implement an interface.. when I create an Homepage instance I create it as a Page(displayobject) so I can move it, attach listerners and add it to stage.. only when I need to call a specific method from the interface I cast it to the interface and for example call an initPage() …

By: jack

jack — Mon, 17 Jan 2011 17:01:54 +0000

@ brecht But still what?

By: asciiman

asciiman — Fri, 17 Dec 2010 19:42:02 +0000

@northmantif
An interface is a signature, while if you extend from a Fruit class you must actually implement the fruit class. How would you implement the getVitamins() function for a Fruit? You can’t, because generic fruits don’t have vitamins. A generic fruit is just a generalization, not actually real.

So interfaces are good for when you need to generalize something that is in common with multiple real things, and you want to create a binding signature for those things.

By: northmantif

northmantif — Mon, 06 Dec 2010 10:34:37 +0000

and what’s the difference between making an Interface, and extending class from a Fruit class i.e. like in the example above, but to pass to the:
function DisplayFruitVitamins(fruit:Fruit):void
{
displayedtext_.Text=fruit.getVitamins ():
}

DisplayFruitVitamins(banana);
??

By: Quakeboy

Quakeboy — Wed, 24 Nov 2010 17:00:33 +0000

Thanks for the quick tutorial.. apt length and to the point explanations.

By: Chris

Chris — Sat, 28 Aug 2010 15:30:01 +0000

Hehe, it’s this short intros that saves the average AS3 starter a lot og “head against the wall/desk” time.