AS3 Custom Event best practices

programming flash
1

I’m just curious how a lot of you handle custom events.

My custom event/s that I will be creating pertain to creating and displaying views. I want to have two separate events dispatched, one to create the view and then one to display the view.

I see three ways of doing this:

  1. Create a single ViewEvent class with two constants CREATE_VIEW and DISPLAY_VIEW. The problem with a single event class is that I would like if possible to use strongly typed parameters. WHen using CREATE_VIEW though, I want to pass an ID that corresponds to the view to create and when I dispatch DISPLAY_VIEW I’d like to pass the view object to display. So I would need to either use two optional parameters, one for viewId of type int and one for view of type DisplayObject and then test for which one exists which I don’t like.

  2. Same as number 1 except use a single generic parameter and check for it’s type to see what the event’s payload is which I don’t like generic parameters either.

  3. Create two separate event classes, a CreateViewEvent and a DisplayViewEvent. This would allow me to use the proper typed parameters, but it seems a little weird since both event actions are so closely related that I feel they should be within the same event class.

So the question is… in general what are everyone’s views on handling a situation like this?

2

Hey kamcknig

I don’t know the exact purpose with why you have 2 separate events, but personally I would go with option 1. I definitely would not pass a generic argument as in option 2.

My decision is based on the purpose of the class, which in this case is to manage all the view events: Creating, displaying, removing, updating, sorting, etc.

Do both CREATE_VIEW and DISPLAY_VIEW events occur simultaneously? Have you considered doing it sequentially instead? So after you pass the viewId and the view is created, only then pass the DisplayObject?

3

With option 1, presumably you’d have a separate handler for each event and would therefore know which event you are handling. Thus you wouldn’t need to check if the property exists. For example:

function handleCreateView(e:ViewEvent):void { trace(e.viewID) }
function handleDisplayView(e:ViewEvent):void {trace(e.view) }