Skip navigation

Flex

Juanjo-kunCalculating status...

Currently Being Moderated

Binding executes an abnormal number of times

Mar 9, 2010 7:14 AM

I'm using the Cairngorm framework. I'm a newbie in Flex, also.

Dispatching a simple CairngormEvent, a command that modifies a property using a setter is executed. This setter has just two lines of code: asign the received value to an internal property, and dispatch the event that the getter is associated to. Why is the getter executing two times? Has Cairngorm something to do with this problem?

Also... if I have this Label component

<mx:Label id="myLabel" text={myVar} />

why is the getter of "myVar" executing 4 times when the application is loaded? Is it normal?

I hope you can help me with these questions. Thank you!

Currently Being Moderated

Flex harUI,

Adobe Employee

Mar 9, 2010 12:40 PM

Report

Generic binding using {} is redundant in order to handle out-of-order
instantiation. If that is a performance issue, directly handling events is
a way to optimize

|
Mark as:

Currently Being Moderated

Juanjo-kun,

Community Member

Mar 9, 2010 2:05 PM

Report

Thanks Flex harUI!

I've been reading for a while and testing a bit more about this "problem". Is data binding something a programmer should avoid until is strictly necessary (never) and should every property change be handled by event handlers?

Maybe customizing the event for the [Bindable] metatag a best way to avoid?

As I say, I'm a newbie in flex, but I can see it really isn't very efficient... to say, this simple "program":

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical"
     width="200" height="200"
     xmlns:utils="utils.*">
     <mx:Number id="num">0</mx:Number>     
     <utils:BindableClass id="bc" />
     <mx:Label id="textTest" text="{bc.counter}"/>
     <mx:Button id="myButton" click="bc.counter = num++" label="¡Sum!"/>
</mx:Application>

using this class:

package utils
{
     public class BindableClass
     {
          private var _counter:Number;
          public function BindableClass()
          {
 
               _counter = 100;
          }
 
          [Bindable]
          public function get counter():Number
          {
               return _counter;
          }
 
          public function set counter(value:Number):void
 
          {
               _counter = value;
          }
     }
}

I just don't understand why the getter executes 4 times each time I click in button myButton.

Do you think is normal?

Thanks again!

Mark as:

Currently Being Moderated

Flex harUI,

Adobe Employee

Mar 9, 2010 5:38 PM

Report

{} binding is a great way to get an app up in a hurry. I use it in most of
my prototypes and will only remove them if I see they are a bottleneck.
Even though it is redundant, a moderate amount of binding shouldn't cost you
that much.

|
Mark as:
Currently Being Moderated

Juanjo-kun,

Community Member

Mar 10, 2010 1:08 AM

Report

Thanks for the help, harUI. I'll use binding in those cases.

Regards

|
Mark as:

Legend

Correct Answers - 10 points
Helpful Answers - 5 points

Choose your region

Security Contact Adobe Report piracy EULAs Permissions and trademarks Careers

Reviewed by TRUSTe: site privacy statement

Use of this website signifies your agreement to the Terms of Use and Online Privacy Policy (updated 07-14-2009).

Flex

Binding executes an abnormal number of times

Mar 9, 2010 7:14 AM

More Like This

Bookmarked By (0)

Legend