How much worse is the performance? Are we talking on the order of a dozen or so extra instructions or orders of magnitude more?
And I guess it would depend on the event being handled, right? Sure, it may be cost-prohibitive for onEnterFrame, but what something like onMouseDown or even onCreationComplete? [Note: I'm using the old style event names as I find it more readable when discussing them.] And what's the expensive part? The binding of the anonymous function object rather than a method, or executing the function object rather than a method? I would assume the latter, since the former should be identical (they're both objects, right?). And doesn't an event listener just store a collection of Function objects? So it's already dispatching through a function object, which makes me think that the overhead is in managing closure, etc? Troy. On 2/15/07, Gordon Smith <[EMAIL PROTECTED]> wrote:
Using anonymous functions as event handlers isn't recommended, as they have worse performance than using methods. - Gordon ------------------------------ *From:* [email protected] [mailto:[EMAIL PROTECTED] *On Behalf Of *Troy Gilbert *Sent:* Wednesday, February 14, 2007 9:44 PM *To:* [email protected] *Subject:* Re: [flexcoders] Re: addEventListener and additional arguments? Remember, functions are objects to (so you can treat them like fancy functors in C++): var functor:Function = function(arg:String):String { return arg + functor["param"]; } functor["param"] = "dolly"; trace(functor("hello"); // outputs "hellodolly" or, for events: var myEventHandler:Function = function(event:MouseEvent):void { trace(myEventHandler["extraData"]); } myEventHandler["extraData"] = "hellodolly"; this.stage.addEventListener(MouseEvent.CLICK , myEventHandler); // when you click on the stage, you'll get the debug message "hellodolly" This'll give you what you're looking for. Not sure what the best way to copy a "functor" object would be... but you could definitely just create a new, separately named Function object for each form item that wraps your function, passing in the the "extraData". Troy. On 2/14/07, Gordon Smith < [EMAIL PROTECTED]> wrote: > > Here's an example of what I meant: > > <?xml version="1.0" encoding="utf-8"?> > <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml";> > > <mx:Script> > <![CDATA[ > > private var foo:int = 7; > > private function clickHandler(event:MouseEvent):void > { > trace(foo); > } > > ]]> > </mx:Script> > > <mx:Button click="clickHandler(event)"/> > > </mx:Application> > Note that the Button's clickHandler() can access the instance variable > 'foo', despite the fact that 'foo' isn't passed to clickHandler() and 'foo' > isn't a property of event.target, which is the Button. > > The reason that clickHandler() can access 'foo' is that when > clickHandler() executes, 'this' is the Application (or whatever component > you're writing). > > - Gordon > > ------------------------------ > *From:* [email protected] [mailto:flexcoders@ yahoogroups.com] > *On Behalf Of *darylgmyers > *Sent:* Wednesday, February 14, 2007 7:42 AM > *To:* [email protected] > *Subject:* [flexcoders] Re: addEventListener and additional arguments? > > Gordon, > I'm pretty new to Flex so I appologize for the additional question. > > Are you saying that I can add an instance property to the target so > that it will be available in the event.target? What I'm actually > doing is creating a set of form fields on the fly using action > script. Some of these fields may be number types with a precision > value. My formatting is done with an event listener which I need to > be able to pass the precision value. > > --- In [email protected] <flexcoders%40yahoogroups.com>, > "Gordon Smith" <[EMAIL PROTECTED]> wrote: > > > > There should be no need to pass additional arguments to the event > > handler method, because -- assuming it is indeed a method of a > class -- > > it can access all the instance properties of that class. So just > set an > > instance property. > > > > - Gordon > > > > ________________________________ > > > > From: [email protected] <flexcoders%40yahoogroups.com> > [mailto:[email protected] <flexcoders%40yahoogroups.com>] On > > Behalf Of darylgmyers > > Sent: Tuesday, February 13, 2007 1:42 PM > > To: [email protected] <flexcoders%40yahoogroups.com> > > Subject: [flexcoders] addEventListener and additional arguments? > > > > > > > > Is there a way to use the addEventListener method and pass > additional > > arguments along with the event? I have a form where I must create > the > > form objects dynamically so I need to use addEventListener for > > formatting, etc. I can not use inline mxml to add the listeners. > > > >
