Question

I’m fairly experienced with Flex 4, but I still haven’t needed frameworks yet (I like to do everything myself) and don’t want to use them either, I know it’s advantages and have learned how to use one of them, but still, no.

How can I dispatch an event in the main application and have a component inside a popupmanager to react to that event? All this dispatching the event within the main app and NOT aiming it to the popupmanager or the component instance, I want to be able to fire the event and not care about who gets it or if anyone reacts to it at all so if that is possible then I wouldn’t care about keeping track of said popups.

I already dispatch an event from the component and receive it in the main application by bubbling the event and therefore being agnostic of each other, now I want it backwards.
Note: I have used singletons, but it’s not the approach I need this time.

Answer 1

It sounds to me you are in desperate need of RobotLegs, you seem to be asking how to to create/use an event bus system in order to de-couple your components which is exactly what robotlegs is amazing at.

One thing you should definitely also look at is ActionScript 3 Signals. Signals is an approach to make strongly typed events like .NET Framework, instead of the magic strings event system, and is a fantastic easy bolt on addition to any Flash/Flex project.

Another way that is common is a mediator/controller singleton pattern. Let’s say this is an automotive application, and we have a service layer that behind the scenes is receiving some data from the server, whilst at the same time our popup is behind displayed. One way we solve this problem is create a singleton based controller for our data like PartsController. It also has some public const Signals like SingalDataUpdated. The popup can now do something like PartsController.SignalDataUpdated.add(OnPartsUpdated). OnPartsUpdated is a local method inside the popup that can now react to the event as necessary and has no coupling to any other UI component. This is typically the approach we take and ensure that no UI component has explicit knowledge of any other UI component, and instead only talk to the controllers. One thing you need to ensure though is when the popup is closed remove the signal lister.

Again though, RobotLegs does most of all these for you and encourages some very great architecural best-pracitces. I would highly recommend you read through their documenation and get familiar with it. It will change your life when you realize how modular and maintainable it helps make your code.

Good luck!

Update regarding context and singletons
The idea regarding a context is to create a single singleton known as your application’s context that stores the instances of what would be your other singletons. Inversion of control (IoC) and RobotLegs just wires things together so it dosen’t look like absolute crap to work with, but you can just use a simple IoC injector like Swiz or SwiftSuspenders which RobotLegs is built upon. So, for example, you might hit a particular controller like:

AppContext.Instance.ProductController.SignalProductAdded.add(OnProductAdded);

But that is a bit ridiculous to try to access everything this way. Here comes RobotLegs to the rescue. Instead define injection rules in your RobotLegs context, so if a component asks for a UserController via an inject metadata tag, everything would get the same UserController. Exactly like a singleton, but correctly so in your component define;

[Inject] public var _objProductController:ProductController;

Now your component can work with the controller object as if it was its own, but instead it was injected in by RobotLegs on construction. For me and and most of my products I build a few base objects like GroupBase, PanelBase, PopupPanelBase, etc. that extend the proper component and already have all the controller injection properties so any component derived from these already connect to the proper controllers as needed.

For your simple project, it’s like easier to roll your own and just create a single singleton for your context to hold your controllers and communicate with application’s context that way. These are all pretty high level architecural decisions and everyone works differently at this level based on their experience, preference, or whatever. The most important thing is that it works for you, and you are comfortable with the architecture. RobotLegs helps make everything very decoupled which has some amazing unforseen benefits later.

Good luck!