Cummon, that's like 15 lines of code, ya bum :)
this is written in gmail, not builder. YMMV. And change it to use weak
referenced listeners, too.
public class ObserveCollection
{
private var watching:ICollectionView;
public var handler:Function;
public function set source(value:ICollectionView) : void
{
if (watching)
watching.removeEventListener(CollectionEvent.CHANGE, changed);
watching = value;
watching.addEventListener(CollectionEvent.CHANGE, changed);
changed();
}
private function changed(ignored:*) : void
{
if (handler != null)
handler();
}
}
On Thu, Aug 14, 2008 at 11:05 AM, Richard Rodseth <[EMAIL PROTECTED]>wrote:
> A little more context. I'm working on a view that builds itself
> dynamically (adding children to various containers) based on a description.
>
> So suppose my view has a property called "description" which has a property
> "things" that is the collection or array.
>
> It's no great hardship to add a listener in the setter for description, but
> I wish I could say something like:
>
> <mx:WatchCollection source="{description.things}" handler="thingsChanged"/>
>
>
>
> On Wed, Aug 13, 2008 at 5:51 PM, Alex Harui <[EMAIL PROTECTED]> wrote:
>
>> There must be some nuance I don't get. What about:
>>
>>
>>
>> <mx:ArrayCollection collectionChange="myFunction" />
>>
>>
>> ------------------------------
>>
>> *From:* [email protected] [mailto:[EMAIL PROTECTED] *On
>> Behalf Of *Richard Rodseth
>> *Sent:* Wednesday, August 13, 2008 5:28 PM
>> *To:* [email protected]
>> *Subject:* Re: [flexcoders] Observing collections
>>
>>
>>
>> Hi Alex,
>>
>> Observe is designed to be used in MXML (it's even billed as the "world's
>> smallest tag") and that's how I use it.
>>
>> http://weblogs.macromedia.com/paulw/archives/2006/05/the_worlds_smal.html
>>
>> As it happens it doesn't implement IMXMLObject.
>>
>> In any case, since it uses regular binding expressions for the "source"
>> property, I believe it has the limitation-by-design I referred to.
>>
>> On Wed, Aug 13, 2008 at 5:17 PM, Alex Harui <[EMAIL PROTECTED]> wrote:
>>
>> Never used Observe, but if it implements IMXMLObject or you subclass and
>> do so, then you can use it in MXML
>>
>>
>> ------------------------------
>>
>> *From:* [email protected] [mailto:[EMAIL PROTECTED] *On
>> Behalf Of *Richard Rodseth
>> *Sent:* Wednesday, August 13, 2008 4:16 PM
>> *To:* [email protected]
>> *Subject:* [flexcoders] Observing collections
>>
>>
>>
>> For some reason I have an aversion to adding event listeners in
>> ActionScript, favouring binding expressions and the Observe tag from Adobe
>> Consulting. Not sure how rational this is, but there you have it. Binding is
>> just so damn elegant.
>>
>> However, collections are a problem. It seems that so often you want to
>> update something if either the collection itself or its contents changes,
>> and you don't really care about the details of the change.
>>
>> I suppose if you're a DataGrid watching its dataprovider you do care and
>> can minimize updates, but in many of the use cases I've encountered, that's
>> not the case - my observer is going to do something with the whole
>> collection (or maybe I've just been lazy about exploiting possible
>> optimizations).
>>
>> Is there anything like the Observe tag that can be instantiated in MXML
>> and can trigger a function call on a COLLECTION_CHANGE event?
>>
>>
>>
>>
>
>
--
"Therefore, send not to know For whom the bell tolls. It tolls for thee."
:: Josh 'G-Funk' McDonald
:: 0437 221 380 :: [EMAIL PROTECTED]
