I Trace, Therefore I Know Where I Am

By Thom Duppstadt

Published June 28, 2011

Best Practices

Rating:

What's good code without good Trace!

Thom Duppstadt

Senior Flash Developer for US based company. I've been coding in Flash for about 7 years. I've been doing AS3 development for the passed 3 years. I have developed more than 50+ complete web and desktop applications done exclusively in Flash. I specialize in advanced coding for the layman. I've developed my own MVC framework and coding library suite for our company's internal development.

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Logical and consistent tracing is essential, particularly when it comes to large projects. I've heard some purists say that your final output should not contain any traces. Agreed; however, you can simply do this with the 'Omit Trace' checkbox in the Flash publishing options. Yes, this should be done for a cleaner output and possible boost in performance but as far as removing all of them from your source code? HELL NO! Trace keeps you sane, it let's you know it's doing or NOT doing what it's suppose to. Just because your program purrs like a kitten doesn't mean you don't have issues. Like events being triggered 100 times unwittingly or objects on the stage that are declaring themselves when you thought you already removed them. Keep your trace! Just organize them and remove what's unnecessary.

As a rule, I leave enough trace to know what the program is doing without having to look at the stage... but removing those needed for a detailed troubleshooting session that has since been resolved. Now formatting your trace.. I use...

trace (" * <ClassName.methodName> information to be traced");

...For submethod data tracing. I simply format it like this.

trace (" * -- Submethod data trace");

...then for alert traces, for example this method did a check and came up possitive for a null object. I use this....

trace ("! <ClassName.methodName> object x returned null");

What's important to note here are the spaces in the beginning of the trace. I add the ' * ' to my trace because doing this will distinguish my trace from a Flash trace and or external class issued trace. Including the class name and the method name in the trace obviously keeps you informed from where the trace is coming from. This might seem tedious at first but it REALLY makes a difference. The alert trace uses '! '. With the initial space removed adding in the '!' again makes this call stand out. I also include empty line traces trace (); to help distinguish key events in program... like going into a new section or whatever. Or a line of underscores to indicate major section divisions.

This seems like a simple thing and to some may even think this seems trivial, but I have enough experience to tell you that if you organize your traces, debugging is much faster and it will keep you up to speed with what your program is doing (before it's too late) HA.

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6 Responses to "I Trace, Therefore I Know Where I Am"

asda Rating: ratingfull

said this on 13 Jul 2011 8:56:18 PM CDT

good!!!!
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Mook Rating: ratingfull

said this on 20 Jul 2011 12:42:55 AM CDT

Hi Thom.

Why do people say that your final output shouldn't contain any traces? Surely it can't have much of an impact on performance?

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Thom Rating: ratingfull

said this on 21 Jul 2011 9:47:25 AM CDT

@Mook: First I'll address the need for trace, then the issue about why your final distribution should not contain trace.

I think some of it is some sort of status thing to say you have ultra clean code cause you don't use trace. I don't think it is from anything truly practical. However, Actionscript.org made the comment to me that 'you could use FlashBuilder and step through the process that basically eliminates the use of the trace command,' But would agree that when it comes to the Flash IDE there is no better method for troubleshooting. I would have to disagree that even with the best step through tools for troubleshooting there is always the need for trace.

It does several things for me.... I can tell what should be happening on the screen based on my <trace, and if it doesn't I can see exactly where the issue was. Yes, a step through tool could do the same thing, but only if you're looking for it. This is what separates the step through tools from trace. With trace I can see anomalies, incorrect sequence of events, and even methods being called that should not be called. The program may be running great so there would be no need for me to step through it, but things like these can be occurring in your program without you even knowing it. The issues may slowly reveal themselves later as the program continues to grow or as the program continues to run. This makes trace a very significant tool that step through tools simply cannot replace. Trace is more proactive.

Another comment made to me by Actionscript.org is the use of tools like Vizzy to help with troubleshooting... This is a very great tool and an oversight in my article. I use this tool quite often which leads to another point for using trace. With tools like Vizzy you can trace SWFs from webpages, EXEs, and Air applications. This allows for in the field troubleshooting. Now when you export your program for final distribution I turn off trace for reasons of security and performance. But sometimes in the field errors or issues can occur that didn't when you tried in your own environment. So for in the field troubleshooting I'll export the program enabling the trace, plug it back in the field and review the trace through Vizzy. Now, that's cool.

Now the reason why you should't have trace in your final distribution is mainly because of security (you may reveal sensitive information from your trace - which is something you should be careful to avoid) and to simply have a clean release. Like most Mac users, the end user only wants to know that the program runs, they don't care about what goes on under the hood. hehe. As for performance, if you don't trace heavy then you are not likely to receive any performance hits but say you have animations and you have trace in an enterFrame (which is a no no BTW) then you might very well cause yer animation to studder. So just be smart about your trace.

Damn that was along reply! HA

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Daniel Rating: ratingfull

said this on 17 Aug 2011 5:36:21 AM CDT

@Mook:

Every trace message gets handled by flash (minor performance hit unless running in flash ide where it has to be printed)

Every trace message is "stored" inside a txt-file somewhere in "your documents" folder and thus flash needs to open that file, write info to it, then save it and redo it during next write interval. Which results in a major performance hit when you are writing a lot of information (entering function, writing something from inside function, leaving function)

Thus it's usually better to encapsulate "tracing" inside a class similar to this "myDebugger.write("some message")". Inside that function you can then have something similar to this

if(runningInFlashIDE)
trace(msg)
else

sendThroughLocalConnectionToDebugger(msg)

That way you wont run into the performance hit from trace-messages when you have no need for them and still get all info you need when you need it.

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Mikey Rating: ratingfull

said this on 28 Nov 2011 1:16:11 PM CDT

Great article man, trace saved my life many times over.

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MSFX Rating: ratingfull

said this on 15 Apr 2012 8:56:57 AM CDT

A while ago I developed a library to extend the build in functionality of tracing...

http://labs.msfx.co.uk/2012/01/17/introducing-tr-ace-an-as3-open-source-debugging-library/

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What's good code without good Trace!

Thom Duppstadt

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6 Responses to "I Trace, Therefore I Know Where I Am"

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