Re: [flexcoders] var myVar : Function = new Function ? examples?

[Kerry Jordan]

On Thu, May 20, 2010 at 6:22 AM, Nick Middleweek  wrote:
> I was going to use the approach for my URLLoader complete event handler 
> function, I was hoping to keep things a bit neater and just pass the .data 
> through to my Cairngorm Command.

We implemented something similar at work. I suggest that instead of
creating a "new" function, simply use a reference to an existing
function. For example, in the class that dispatches the command,
create a function such as...

private function processCmd( /* result data */ ):void
{
// functionality to handle result here
}

Then, add a function property to the command event...

private var _result:Function;

public function get result():Function
{
return _result;
}

public function set result( value:Function ):void
{
_result = value;
}

You can set the function in the command event (cmd) by the following
statement...
cmd.result = processCmd; // note that parentheses are not included or
it would be a function call instead of reference

In the processing of the command event, when you have received data
simply call...
if ( cmd.result != null )
{
cmd.result( /* result data */ );
}

Does that make sense? Does it address your problem?

Kerry

Re: [flexcoders] var myVar : Function = new Function ? examples?

[Oleg Sivokon]

Neva! :D

Just never use anonymous functions in AS3, they are badly implemented and,
they aren't truly anonymous. You cannot design a first order functions in
ECMAScript languages, nada!, whatever anyone is going to say about that :)
Simply give it a normal method, this is the simplest and the best way to go
about it. When you pass a function of that kind, especially if you want that
to be an event listener these things will happen:

1. Each time you call the function that adds a listener *new* anonymous
function is generated.
2. This sort of listener will not be garbagecollected normally. It
essentially violates the rule of the stack that local variables should not
outlive their scope. The parent function scope is added to that anonymous
handler, so, by using it you may potentially run into hard to identify
memory leaks.
3. These functions and JIT compiler aren't good friends. Which means they
are going to be in general slower (sometimes, however you may compensate it
by not invoking it with arguments, so, you'll save on creating arguments
array, but that's a poor compensation).
4. Difficult to debug. These functions will appear like either:

or
MethodInfo-(123)
in the call stack trace.

Lastly, the way that you have it now, if your server will take a bit to long
to reply, both the loader and its handler will be GC'ed, because they are
not referenced anywhere outside the function, so, potential of IO error
events and unpredictable behavior.

Best.

Oleg

Re: [flexcoders] var myVar : Function = new Function ? examples?

[Nick Middleweek]

ok, thanks Oleg...

I was going to use the approach for my URLLoader complete event handler
function, I was hoping to keep things a bit neater and just pass the .data
through to my Cairngorm Command.

What are your thoughts on the idea?

something like this...


private funtion loadXML(path:String) : void
{
   var myReq : URLRequest = new URLRequest(path);
   var myLoad : URLLoader = new URLLoader();

   var completeHandler : Function = function (evt : Event) : Type { //
handle data load  }


  myLoad.addEventListener(Event.COMPLETE, completeHandler)
  myLoad.load(myReq);

}


Cheers,
Nick


On 20 May 2010 11:46, Oleg Sivokon  wrote:

>
>
> You cannot construct a function like that. What you can do is more like
> this:
>
> var f : Function = function (arguments) : Type { function body }
>  
>



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Sent by Nick Middleweek ( { email: n...@middleweek.co.uk, mobile: +44(0)774
035 5424 } );

Re: [flexcoders] var myVar : Function = new Function ? examples?

[Oleg Sivokon]

You cannot construct a function like that. What you can do is more like
this:

var f : Function = function (arguments) : Type { function body }

[flexcoders] var myVar : Function = new Function ? examples?

[Nick Middleweek]

Hello,

I can't find any examples on how to create Functon variables?

Does anyone have any to hand please?


Thanks,
Nick


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Sent by Nick Middleweek ( { email: n...@middleweek.co.uk, blog:
http://blog.middleweek.co.uk } );