Flex Template Component

This week on InsideRIA, I blogged about Flex Template components. My mandate for that blog is to talk more about ideas than showing code, but I had a feeling that someone would ask to see code on this one, so I put together an example of code that is similar to the component I show a screen shot of in that post for the curious.

The example linked to below has View Source enabled:

Flex Template Component Example.

Another good itemRenderer Resource

The longer I use Flex, the more firmly I believe that the key to understanding it is the component life cycle. Specifically, the life cycle as it applies to item renderers. Today on Flex Coders, Douglas Knudsen posted a link to this great presentation on the component life cycle by Eli Greenspan. I can't for the life of me figure out how to bookmark to a pdf, but if I post a link here, I'll be able to find it forever :-).

Great ItemRenderer Resource

I really struggle with itemRenderers--what goes where to make what you want to occur happen when you want it to. So I've been talking to various people and reading, reading, reading trying to make sense of it all. From the posts on the yahoo FlexCoders group, it seems like I'm not the only one experiencing confusion.

I think the biggest problem is that there don't seem to be many "from the ground up" resources on this subject. But that doesn't mean there aren't any. In addition to the Flex help and LiveDocs, which, let's face it, confuse us as much as inform us, there are several blogs that tackle this subject. Today I found Peter Ent's blog, which contains a five part series just on itemRenderers. Thanks, Peter!

Dispatching Events

I'm thinking I'm probably extra stupid, but I kind of got the impression from the Event handling docs that if you wanted to send out your own events, you had to have your own events class. It seemed to me there was something magical in the constants defining event names in your events class that somehow made the events so named "your" events. It turns out that if you want to dispatch an event "this is an event" then it really is as simple as

dispatchEvent(new Event("this is an event"));

Then all you have to do is add an event listener for "this is an event". There's no more magic to it than that. The event just needs to be called the same thing on both sides, and that is what the constants make sure of. But they're not required.

Now, if you want to pass more information in an event, such as whether a click on a Multiple Choice Question is right or wrong, then you'd need your own Event class. But for simply broadcasting an event you know is yours, you just send out an event as above. Duh.

I figure most people reading this are not as "challenged" as I am, but hopefully this helps someone anyway.

Update 7/3/2008: When a component is dispatching events, it should also "announce" what events are available on it with an Event metadata tag, such as [Event (name="thisIsAnEvent" type="flash.events.Event")]. This allows you to use it in MXML without a compiler error. I honestly don't know whether multi-word event name, as stated in my original example, would cause an error or not.