Synchronous & Asynchronous Error Handling

[tptompkins]

I'm starting to put together my error handling framework and have a question around Synchronous & Asynchronous Error Handling.

I've been able to use try{} catch{} blocks for handling synchronous errors and I've also tested asynchronous error handling by adding an event listener to call an error handling method when using the NetConnection class.

What I'm wondering is if it's possible to throw an Error from my asynchronous event error handling method and have a parent method catch it in a try{} catch{} block. I'm assuming it isn't possible since I can't get it to work I can throw the error from the method and have it print in the output window but I can't catch it!

Thanks,

Tommy

[jsebrech]

No, a try / catch block will only catch exceptions that were raised in a deeper level of a thread of execution. When you perform an asynchronous function, this runs as a new thread of execution.

Instead of exceptions you could use event dispatching as a mechanism to inform the necessary classes of the failure.

[tptompkins]

Event dispatching huh? Hmm...I think I'll look into that more. But isn't event dispatching for when you want to dispatch your own "custom" events? Would I still use this if I wanted to handle events such as NetStatusEvent.NET_STATUS?

Tommy

[Assertnfailure]

You can dispatch custom or built-in events.

You can also do something like:

private function errorHandler(evt:ErrorEvent):void{
   this.dispatchEvent(evt);
}

[tptompkins]

I tried this but it's getting caught in a continuous loop and eventually ends in a stack overflow. Here's my code:

package 
{    
	import flash.net.NetConnection;    
	import flash.net.ObjectEncoding;   
	import redcart.constants.RCConstants;
	import flash.events.NetStatusEvent;
	import flash.text.TextField;
	import flash.text.TextFieldAutoSize;
	
	public class RCNetConnection extends NetConnection
	{                
		public function RCNetConnection()        
		{        
			try{
				objectEncoding = ObjectEncoding.AMF3; 
				
				var gatewayLocation:String = "http://" + RCConstants.getRCDomain() + "/RedCart/v3/rcFlash/amfphp/gateway.php";
				trace("About to connect to gateway: " + gatewayLocation);
				
				// Connect to gateway
				connect(gatewayLocation);   
				this.addEventListener(NetStatusEvent.NET_STATUS, errorHandler);
			}
			catch (err:Error)
			{
				trace("An error has occurred.");
				trace("ERROR MSG: " + err.message);
			}
		}    
		
		
		private function errorHandler(evt:NetStatusEvent):void
		{
			if(evt.info.level == "error")
			{
				trace("Gateway connection failed: " + evt.info.code);
				dispatchEvent(evt);
			}
			else
			{
				trace("RC Gateway Connection Status: " + event.info.code);
			}
		}
	}
}

I'm guessing that it's getting stuck in a loop because the existing listener keeps seeing the event and calling the errorHandler() method. So what am I doing wrong?

Thanks,

Tommy

[tptompkins]

Nevermind - I got it figured out now. I created a custom event and dispatched that to a method on a custom error manager class.