Remove Event Listener : Best Practice

This quesiton isn't really keeping me from progressing on my current project, but I was wondering what the best practice was. If I'm about to remove an item with removeChild(), should I first remove any Event Listeners that were on that object or do those get removed and cleared from memory automatically when the child is removed?
Thanks,
Dave

As Kalisto mentioned, the listeners will only be removed automatically if you use weak reference when you add it:
myObject.addEventListener(MouseEvent.CLICK, someFunction, false, 0, true);
The true on the end specifies to use weak ref. If you don't use that (you always should) then you will have to remove it manually or it will hang around forever.
Also, removeChild simply removes the object from the display list... it's still in memory. Set it to null if you want to truly clear it.

Similar Messages

Help regarding event flow/event listening best practices

Hi, I'm making a flash memory card game to learn more about
to actionscript.
I have:
- a main class that loads on start. This class instantiates
a:
- CardLoader class that imports graphical assets and uses
these to create all my cards:
- Card class that represents individual card. Can dispatch
CardEvent when clicked:
- CardEvent contains info on the Card that dispatched it,
such as the cards ID number and the ID of it's matching card.
What I want to do is to have another object to act as a game
logic handler.
Example:
- Card 1 was clicked, dispatches CardEvent that ends up with
the LogicHandler.
- Card 2 was clicked and also dispatches event.
LogicHandler compares these two cards and does the
appropriate thing depending on they being a match or not.
Now, the big questions is, how do I get this event to the
LogicHandler?
My custom CardEvent has it's bubbles property set to true.
So, I can manage to get such an event all the way back to my main
class, in this order: CardEvent > Card > CardLoader >
Main.
The problem arises when I want to have my LogicHandler class
created by Main. When my CardEvent bubbles back, it does not go
through this LogicHandler since it is not part of the event flow on
it's way back.
Questions: How do I, following the best possible programming
practises, send the event the way I want it to go?
I can only think of one solution myself, being that inside my
Main method I set up an eventlistener that listens for this event
and passes it on downwards, in this case to the LogicHandler. Sure,
it's only a few lines of code in the main method, but what if you
have 50 different events in a larger project that needs the same
treatment?
Your main method will be a mess by then!
How would you do it?

Ok let me see if I get this straight:
In my example, I would have to pass a reference of the
LogicHandler to my Card class.
In my Card class, I have something like:
logicHandler.addDispatcher(this);
this being the Card of course.
Inside LogicHandler class I have the addDispatcher method
that calls the addEventListener method.
So far so good?
The addDispatcher method adds an eventlistener to the Card
object, from what I can tell. But it does it inside the
LogicHandler, thus the method that is called by the
addEventListener can be inside the LogicHandler?
To put it in other words, what's confusing me is that the
Listener object adds an EventListener to the dispatching object.
Logically for me the listener should add a listener to itself?
The way I first did it in my Card class was:
testevent = new CardEvent(CardEvent.CLICK);
dispatchEvent(testevent);
And then set up the EventListener in the object that I wanted
to receive the event.
I'm sorry I don't understand this, despite your obviously
good explanations (I think I understand a lot more now, just not
the best approach). I will look into the callback functions, sounds
a lot interesting as well

Can't remove event listener from Image

I'm clearly missing something and would appreciate some help. I'm trying to run an event handler when an Image completes loading, then remove the handler so that it won't run again should the image be reloaded later.
The problem that I'm having is that the event handler simply wont' go away, despite calling removeEventListener on the Image object.
The following example demonstrates the problem (the example doesn't actually do anything useful...it's just the shortest example to demonstrate the problem). (To run the app, you'll have to provide any ol' JPEG file named "myImage.jpg" in the "src" directory of your project).
What I expect to happen is :
     1) on startup, the image loads and loadComplete() runs.
     2) loadComplete removes the event Listener so that subsequent re-loads won't re-fire the handler. I only want the handler to run once.
     3) "loadComplete" shoudl be displayed in the Debug console.
     4) A button click should display only "Changing Image" in the Debug console
What I get instead is that the loadComplete handler isn't removed, and every time I click the button, loadComplete runs when the image is re-loaded   (i.e., every button click results in both "Change Image" AND "loadComplete" being displayed in the Debug console).
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
    <mx:Image width="655" height="181" source="myImage.jpg" id="myImage" autoLoad="true" scaleContent="true" complete="loadComplete()" x="100" y="100"/>
    <mx:Button x="100" y="341" label="Button" click="click(event)"/>
    <mx:Script>
        <![CDATA[
            private function loadComplete():void
                trace ("loadComplete");
                myImage.removeEventListener("complete", loadComplete);
            private function click(evt:Event):void
                trace ("Changing Image");
                myImage.load("myImage.jpg");    // Reload same image; it's just an example
        ]]>
    </mx:Script>
</mx:Application>

Hi,
You can remove only event listeners that you added with the addEventListener() method in an ActionScript block. You cannot remove an event listener that was defined in the MXML tag, even if it was registered using a call to the addEventListener()method that was made inside a tag attribute.
Check this page for reference.
http://livedocs.adobe.com/flex/3/html/help.html?content=events_05.html
You can modify the code a bit a get it working
<mx:Image width="655" height="181" id="myImage" scaleContent="true"
          x="100" y="100"
          creationComplete="myImage_creationCompleteHandler(event)"/>
private function myImage_creationCompleteHandler(event:FlexEvent):void
     myImage.addEventListener("complete",myImage_completeHandler);
     myImage.load("myImage.jpg");
private function myImage_completeHandler(event:Event):void
     myImage.removeEventListener("complete",myImage_completeHandler);

Remove event listener from loaded external swf

I have a main movie timeline that loads an external swf. When I unload the swf from the main timeline I get an error from this: my_FLVPlybk.addEventListener(VideoEvent.COMPLETE, vidEnd);
is there any way to remove the event listener from the loaded swf from the main timeline?
THANKS!

if you're publishing for fp 10+, use unloadAndStop() applied to your swf's loader. that has a fair chance of solving the problem.
if that fails, you should explicitly stop my_FLVPlybk.

How to remove event listener when all the MoviClip are off the stage

Hi i am newbie to as3,
    I am creating animation using as3 in which i duplicate the circle ten time,then pushing into an array and giving random motion. When all the duplicate object goes outside the stage then i should remove the event listener. But right now when one duplicate object goes off the stage the event listener is removed. Thanks in advance

//---------code for creating random bubble movement------//
var bubbleNo:Number = 10;
var vx:Number = .3;
var vy:Number = .5;
var bubbles:Array = new Array();
var bubbleRadius:Number = 9;
var myColor:ColorTransform = this.transform.colorTransform;
init();
function init():void {
for(var i:Number = 0; i<bubbleNo; i++){
          var bubble = new newBall();
bubble.x = Math.random() * stage.stageWidth;
bubble.y = Math.random() * stage.stageHeight;
//bubble.color = Math.random
//trace("bubble.x=="+bubble.x+"bubble.y=="+bubble.y);
bubbles.push(bubble);
myColor.color = Math.random() * 0xFFFFFF
bubble.transform.colorTransform = myColor;
addChild(bubble);
          addEventListener(Event.ENTER_FRAME,createBubble);
//addEventListener(Event.ENTER_FRAME,createBubble);
function createBubble(event:Event):void{
for(var k:Number = bubbles.length-1; k>0; k--){
          var bubble = (newBall)(bubbles[k]);
          bubble.x += vx;
          bubble.y += vy;
          if(bubble.x - 18 > stage.stageWidth || bubble.x + 18 < 0 || bubble.y - 18 > stage.stageHeight || bubble.y + 18 < 0){
                    removeChild(bubble);
                    bubbles.splice(k, 1);
                    //trace("out"+bubbles.length);
                    if(bubbles.length <= 0 );
                              removeBubble();
                              trace(bubbles.length);
                              //removeEventListener(Event.ENTER_FRAME,createBubble)
                    trace("all Bubbles cleared");
                    function removeBubble():void{
                              removeEventListener(Event.ENTER_FRAME,createBubble)

Removing event listener from a button.

I've added a "click" event listener to a button, but I'd like to remove it once the button is clicked, so it's not active/clickable any longer. Here's the basic code:
sym.$('button').click(function(){
     //here I need to make this button not clickable any longer
Thank you.

one way...
sym.$('button').click(function(){
     //here I need to make this button not clickable any longer
     // do smething here then unbind click handler
            sym.$('button').unbind( "click" );
unbind documentation here.
hth
Darrell

Removing event listener on ROLL_OUT

I'm trying to build a scrolling thumbnails from scratch for my first time and i can get the thumbs to scroll when the mouse rolls over the scroll arrow, but i can't get it to stop scrolling once the mouse rolls out. here's what I have if someone can help point out where the function should go.
leftscroll_mc.addEventListener(MouseEvent.ROLL_OVER, scrollLeft);
function scrollLeft(e:MouseEvent):void {
addEventListener(Event.ENTER_FRAME, goLeft);
function goLeft(e:Event):void {
grds1_mc.x+=6;
grds2_mc.x+=6;
grds3_mc.x+=6;
grds4_mc.x+=6;
grds5_mc.x+=6;
grds6_mc.x+=6;
grds7_mc.x+=6;
grds8_mc.x+=6;
grds9_mc.x+=6;
grds10_mc.x+=6;
grds11_mc.x+=6;
leftscroll_mc.addEventListener(MouseEvent.ROLL_OUT, lremoveFast);
function lremoveFast(e:MouseEvent):void {
leftscroll_mc.removeEventListener(Event.ENTER_FRAME, scrollLeft);
I've tried moving the entire roll_out function all over the place but I would get errors not being able to find lremoveFast but either way I can't get it to funciton

The first thing you need to do is to move all of those functions outside of the function they are in. You should not nest named functions because they do not compile. When you assign the ENTER_FRAME listener, to remove it you must remove it from where it is added, and be sure you're removing the one added--you have things jumbled up there--wrong target, wrong listener. Another thing you could do is reduce your code by using a loop for all those similarly named movieclips.
leftscroll_mc.addEventListener(MouseEvent.ROLL_OVER, scrollLeft);
leftscroll_mc.addEventListener(MouseEvent.ROLL_OUT, lremoveFast);
function scrollLeft(e:MouseEvent):void {
     this.addEventListener(Event.ENTER_FRAME, goLeft);
function lremoveFast(e:MouseEvent):void {
    this.removeEventListener(Event.ENTER_FRAME, goLeft);
function goLeft(e:Event):void {
     for(var i:int = 1; i<12; i++){
          this["grds"+String(i)+"_mc"].x+=6;

UI Design - Best Practice when Two UIs Trigger Same Event

I have an application that allows users to take actions using several methods - right-click context menu selection, menu bar selected, key strokes, etc. I was wondering if anyone had any suggestions as to teh best practices for handling this in Cairngorm...
Is it best to dispatch the same Cairngorm event in several places? I know this is one of the major reasons to use MVC, but, I hate to create duplicate code - maintenance is pain.
Would is be considered good practice to have the container that serves as a parent for the context menu, menu bar, etc. to listen for events from these components, and then dispatch the Cairngorm Event?
Thanks.

Would it be considered good practice to have the container that serves as a parent for the context menu, menu bar, etc. to listen for events from these components, and then dispatch the Cairngorm Event?
Yes, this is described by Steven Webster in his series of articles on Cairngorm.
Dispatching the same Cairngorm event from different locations is a perfectly regular practice. This is even an advantage. The same code (the command, the delegate) can be triggered from different places.

Best practice for adding and removing eventListeners?

Hi,
What is the best practice in regards to CPU usage and performance for dealing with eventListeners when adding and removing movieclips to the stage?
1. Add the eventListeners when the mc is instantiated and leave them be until exiting the app
or
2. Add and remove the eventListeners as the mc is added or removed from the stage (via an addedToStage and removedFromStage listener method)
I would appreciate any thoughts you could share with me. Thanks!
JP

Thanks neh and Applauz78.
As I understand it, the main concern with removing listeners is to conserve memory. However, I've tested memory use and this is not really an issue for my app, so I'm more concerned if there will be any effect on CPU (app response) if I'm constantly adding and removing a list of listeners every time a user loads an mc to the stage, as compared to just leaving them active and "ready to go" when needed.
Is there any way to measure CPU use for an AIR app on iOS?
(It may help to know my app is small - I'm talking well under 100 active listeners total for all movieclips combined.)

Best Practice to use Event trigger in 3.1

All,
I am trying to start some publication upon the copy of a file.txt generated by an ETL tool
Basically I would have like a cron job that would generate the txt file in a specific folder, then Business objects event server would trigger my publication or the refresh of my report base of the file.txt
so far all is easy to setup, I would like to know if in 3.1 we have a best practice to remove this file once the job has been triggered ?
I can always create a cron job on the side that would delete the files after X minutes, but I thought it would be better if in the system there is something that would delete this file after the job is finished
thanks a lot in advance
Philippe

Hi,
If I use the entire PR it is true but if I use only 50% of it. The commitment of the PR disappears and the commitment of the PO is 50% of the PR. And I want to found a way to transfert only the % of the commiment used in the PO.
Best regards

Best practice for passing parameters to a Timer event handler?

The code hinting is suggesting that I use a Timer object rather than setTimeout or setInterval, however I need to pass a parameter to the timer handler.
What is the best practice for doing this?
+ Subclass Timer?
+ Subclass TimerEvent?
+ Global variable?
+ other?
Thanks

Hmm. I don’t think I would’ve chosen that option. I would probably create a class that listens for the TimerEvent dispatches a custom event. Unless there is information you need in TimerEvent, I don’t see a need to extend it.

Best practice for responding to keyDown event

I am writing my first Cocoa application. It's a simple utility app -- a calculator. I've got everything working, the last thing I want to add is I want the app to respond to key press events. So, you could click the "4" button with the mouse, or you could just press the "4" key on the keyboard. I'm reading all the event handling documentation, but I'm not picking up on the recommended approach for getting an NSResponder (or NSView) that handles the event.
I can make a subclass of NSWindow and tell the interface builder to make the main window of that type. Then when I override the keyDown message in my new NSWindow subclass, it gets the events, but I'm not sure how to connect it to my application delegate class (since I basically just want to switch on the key pressed and call the corresponding message in the delegate that the button "select" action targets.
Or, I think I heard something about doing this by changing the super class of the application delegate class from NSObject to NSView, or NSResponder or something. I haven't poked at that idea much, but I'm not sure how to actually get the application delegate object then actually set up as the first responder (I think that's what I'd want to do).
So, I'm hoping someone can give me specific directions on how/where I should implement my keyDown method, but I'd also like to understand what the recommended "best practice" is for doing this. What would Apple say is the right architecture for doing this? I'm as much interested in learning how to make this work as learning the Apple design pattern behind it.
The structure of my program is as follows:
I have one nib file (actualy a .xib) where I've designed my window with a textbox for display and a hand-ful of buttons. I've registered outlets and actions from there to the AppDelegate class (the one that the standard project template sets up for you). Following the MVC pattern, I then have a Calculator class that the AppDelegate initializes and all the actual logic of the calculator is in that class. The AppDelegate basically just responds to messages from the buttons, passes them along to methods in the Calculator class, and then asks the Calculator for the current display value and updates that back into the textbox. So, the graphical elements in my nib file are the "view", the AppDelegate is the "controler" and the Calculator class is the "model". Right?
So, who is supposed to be handling keyDown events? Seems like the view should capture them and send them to the controller, but how do I set that up?

Dear Noppong,
You can do it with multiple ways like :-
1. Get the current host name and make complete URL with using host name for the webdynpro iview.
request = (IPortalComponentRequest) this.getRequest();
HttpServletRequest req = request.getServletRequest();
StringBuffer strURL = req.getRequestURL();
2. Create the KM Document or Link for webdynpro Iview OR Create the WPC Web Page for the webdynpro ivew
Refer to [http://help.sap.com/saphelp_nw70/helpdata/en/06/4776399abf4b73945acb8fb4f41473/frameset.htm|http://help.sap.com/saphelp_nw70/helpdata/en/06/4776399abf4b73945acb8fb4f41473/frameset.htm]
[http://help.sap.com/saphelp_nw70/helpdata/en/06/4776399abf4b73945acb8fb4f41473/frameset.htm|http://help.sap.com/saphelp_nw70/helpdata/en/06/4776399abf4b73945acb8fb4f41473/frameset.htm]
[http://help.sap.com/saphelp_nw70ehp1/helpdata/en/ff/681a4138a147cbabc3c76bde4dcdbd/content.htm|http://help.sap.com/saphelp_nw70ehp1/helpdata/en/ff/681a4138a147cbabc3c76bde4dcdbd/content.htm]
Hope it will helps
Best Regards
Arun Jaiswal

Exchange Best Practices Analyzer and Event 10009 - DCOM

We have two Exchange 2010 SP3 RU7 servers on Windows 2008 R2
In general, they seem to function correctly.
ExBPA (Best Practices Analyzer) results are fine. Just some entries about drivers being more than two years old (vendor has not supplied newer drivers so we use what we have). Anything else has been verified to be something that can "safely be ignored".
Test-ServiceHealth, Test-ReplicationHealth and other tests indicate no problems.
However, when I run the ExBPA, it seems like the server on which I run ExBPA attempts to contact the other using DCOM and this fails.
Some notes:
1. Windows Firewall is disabled on both.
2. Pings in both directions are successful.
3. DTCPing would not even run so I was not able to test with this.
4. Connectivity works perfectly otherwise. I can see/manage either server from the other using the EMC or EMS. DAG works fine as far as I can see.
What's the error message?
Event 10009, DistributedCOM
"DCOM was unable to communiate with the computer --- opposite Exchange server of the pair of Exchange servers--- using any of the configured protocols."
This is in the System Log.
This happens on both servers and only when I run the ExBPA.
I understand that ExBPA uses DCOM but cannot see what would be blocking communications.
I can access the opposite server in MS Management Consoles (MMC).
Note: the error is NOT in the ExBPA results - but rather in the Event Viewer System Log.
Yes, it is consistent. Have noticed it for some time now.
Does anyone have any idea what could be causing this? Since normal Exchange operations are not affected, I'm tempted to ignore it, but I have to do my "due diligence" and inquire.
Please mark as helpful if you find my contribution useful or as an answer if it does answer your question. That will encourage me - and others - to take time out to help you.

Hi David,
I recommend you refer the following article to troubleshoot this event:
How to troubleshoot DCOM 10009 error logged in system event
Why this happens:
Totally speaking, the reason why DCOM 10009 is logged is that: local RPCSS service can’t reach the remote RPCSS service of remote target server. There are many possibilities which can cause this issue.
Scenario 1:
The remote target server happens to be offline for a short time, for example, just for maintenance.
Scenario 2:
Both servers are online. However, there RPC communication issue exists between these two servers, for example: server name resolvation failure, port resources for RPC communication exhaustion, firewall configuration.
Scenario 3:
Even though the TCP connection to remote server has no any problem, but if the communication of RPC authentication gets problem, we may get the error status code like 0x80070721 which means “A security package specific
error occurred” during the communication of RPC authentication, DCOM 10009 will also be logged on the client side.
Scenario 4:
The target DCOM |COM+ service failed to be activated due to permission issue. Under this kind of situation, DCOM 10027 will be logged on the server side at the same time.
Event ID 10009 — COM Remote Service Availability
Resolve
Ensure that the remote computer is available
There is a problem accessing the COM Service on a remote computer. To resolve this problem:
Ensure that the remote computer is online.
This problem may be the result of a firewall blocking the connection. For security, COM+ network access is not enabled by default. Check the system to determine whether the firewall is blocking the remote connection.
Other reasons for the problem might be found in the Extended Remote Procedure Call (RPC) Error information that is available in Event Viewer.
To perform these procedures, you must have membership in Administrators, or you must have been delegated the appropriate authority.
Ensure that the remote computer is online
To verify that the remote computer is online and the computers are communicating over the network:
Open an elevated Command Prompt window. Click Start, point to
All Programs, click Accessories, right-click
Command Prompt, and then click Run as administrator. If the
User Account Control dialog box appears, confirm that the action it displays is what you want, and then click
Continue.
At the command prompt, type ping, followed by a space and the remote computer name, and then press ENTER. For example, to check that your server can communicate over the network with a computer named ContosoWS2008, type
ping ContosoWS2008, and then press ENTER.
A successful connection results in a set of replies from the other computer and a set of
ping statistics.
Check the firewall settings and enable the firewall exception rule
To check the firewall settings and enable the firewall exception rule:
Click Start, and then click Run.
Type wf.msc, and then click OK. If the
User Account Control dialog box appears, confirm that the action it displays is what you want, and then click
Continue.
In the console tree, click Inbound rules.
In the list of firewall exception rules, look for COM+ Network Access (DCOM In).
If the firewall exception rule is not enabled, in the details pane click
Enable rule, and then scroll horizontally to confirm that the protocol is
TCP and the LocalPort is 135. Close Windows Firewall with Advanced Security.
Review available Extended RPC Error information for this event in Event Viewer
To review available Extended RPC Error information for this event in Event Viewer:
Click Start, and then click Run.
Type comexp.msc, and then click OK. If the
User Account Control dialog box appears, confirm that the action it displays is what you want, and then click
Continue.
Under Console Root, expand Event Viewer (Local).
In the details pane, look for your event in the Summary of Administrative Events, and then double-click the event to open it.
The Extended RPC Error information that is available for this event is located on the
Details tab. Expand the available items on the Details tab to review all available information.
For more information about Extended RPC Error information and how to interpret it, see Obtaining Extended RPC Error Information (http://go.microsoft.com/fwlink/?LinkId=105593).
Best regards,
Niko Cheng
TechNet Community Support

Best Practices for Removing Shots from BDMV folder

CS6 Production Premium Suite
Win7x64
Canon XA10
I would appreciate feedback on the best practices for the following situation:
Using Windows Explorer, I copy the BDMV folder from the XA10 to my Talk2 project folder.
The BDMV folder has three one hour shots (talks) where each shot is one hour called Talk1, Talk2, and Talk3.
Each shot consists of several MTS files in the STREAM folder since MTS files have a maximum file size so a new MTS file is created when a given MTS file reaches the maximum file size.
Since I only want to have Talk2 stuff in my Talk2 project folder, I need to remove the Talk1 and Talk3 stuff from the BDMV folder.
I delete the Talk1 and Talk3 MTS files from the STREAM folder.
I delete the Talk1 and Talk3 CPI files from the CLIPINF folder.
I leave the PLAYLIST folder as is.
Using the Media Browser, I import Talk2 (which consists of two MTS files).
I edit the clip.
This procedure seems to work, but I do not know if there are any "got you" issues.
Thanks in advance.

Oh, don't do it that way. I know a lot of people do, heck, my boss does, but it's just asking for trouble.
Treat your card as if it was your original tape master (because it is). It is the most important thing you have. Don't delete or move any part of it.
If you want to break up the talks, do it as you shoot them. Use separate cards for each talk and archive each one separately. There is too much valuable information in the structure of the card format. You may not need it now but your editing program may need it later.
Hard drive space is cheap but digital recordings are priceless

Best practice for listeners for multiple oracle homes - 1 listener?

I have a machine with 9i and 10g on it, and I have set up a 10g listener to serve connections to the 9i and 10g databases.
Is this best practice, or is it better to have two listeners - a 9i listener for th 9i databases and a 10g listener for the 10g databases?

HI,
Are they two production databases ? In this case, like Laurent said, perhaps it's better to have one listener per instance, if one shutdown, it doesn't disturbe the other.
Are they different application level (1 for dev, 1 for validation...), here too, perhaps it's better to have one listener per instance, if one shutdown, it doesn't disturbe the other.
Are they two development databases ? In this case, you can to have one listener for all databases
I don't think that there is only one way, but there is too many configuration which make one solution is better that other.
Nicolas.

Remove Event Listener : Best Practice

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