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Man: Doctor, it hurts when I do this.
Man: Doctor, it hurts when I do this.
Doctor: Don’t Do that. Next!

Introductions
Introductions
Better Mistakes make for Better Developers
Race Conditions
Cross Domain Issues
Performance Problems
Bindings, Bindings, Bindings
If only someone warned me
Summary

Jeff Tapper (jtapper@digitalprimates.net)
Jeff Tapper (jtapper@digitalprimates.net)
Senior Consultant – Digital Primates
Building Internet Applications since 1995
Authored 11 books on internet technologies
Adobe Certified Instructor for all Flex, AIR, Flash, and ColdFusion courses
http://blogs.digitalprimates.net/jefftapper
Twitter: jefftapper

Developers who:
Developers who:
Have some experience with Flex
Have a sense of humor
If this isn’t you, you should just leave

There is no silver bullet
There is no silver bullet
Writing good code can be hard
Avoiding common pitfalls helps

The term Race Condition initially comes from electrical engineering
The term Race Condition initially comes from electrical engineering
A race condition is a flaw in an electronic process whereby the output of the process is unexpectedly and critically dependent on the sequence or timing of other events
The same concept applies to programming
Operations can complete at different times based on outside influences.

Race (or timing) conditions are the single most common type of problem experienced in Flash Development.
Race (or timing) conditions are the single most common type of problem experienced in Flash Development.
We have several tools at our disposal to help avoid Race conditions
Component lifecycle
Events
Bindings
Etc.

Life in a ViewStack
Life in a ViewStack

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Asynchronous Nature of Component Creation
Asynchronous Nature of Component Creation

Lifecycle events – BackgroundLabelFix2
Lifecycle events – BackgroundLabelFix2

Asynchronous Data Access
Asynchronous Data Access

DataBinding – lastResult
DataBinding – lastResult
Events – wait for result events
I’m assuming you already know this part
Complexity is managing when several responses are dependent on each other

Treat the problem, not the symptom.
Treat the problem, not the symptom.
don’t use creationPolicy=“all, ” fix the underlying problem
Be aware of the Flex component lifecycle
Understand what happens synchronous vs asynchronously
If it’s not unexpected, its not a race.

What are different domains
What are different domains
How do you handle loading data between different domains
crossdomain.xml
Security.loadPolicyFile();
Marshall Plan
Cross SDK Interop
Application Domains
Security Domains

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If one swf needs to interact with a swf loaded from a different domain
If one swf needs to interact with a swf loaded from a different domain

The Flash Player can be a high performance Virtual Machine, if YOU don’t screw it up.
The Flash Player can be a high performance Virtual Machine, if YOU don’t screw it up.
Have pity on the client (machine)
Understand how and when the screen is drawn.

Whenever possible, setStyle() before the object is on the display list
Whenever possible, setStyle() before the object is on the display list
private var _submitButton:Button;
protected override function createChildren():void {
   _submitButton = new Button();
   _submitButton.label = 'Submit';
   addChild(_submitButton);
   _submitButton.setStyle('backgroundColor', 0x123456);
}

private var _submitButton:Button;
private var _submitButton:Button;
protected override function createChildren():void{
Super.createChildren()
if (!_submitButton){
_submitButton = new Button();
_submitButton.label = 'Submit';
       _submitButton.setStyle('backgroundColor', 0x123456);
addChild(_submitButton);

}
}

Avoid calling setStyle() in update display list, unless its actually necessary.
Avoid calling setStyle() in update display list, unless its actually necessary.
No:
_submitButton.setStyle('backgroundColor', currentBackgroundColor);
Yes:
if (_submitButton.getStyle('backgroundColor') != currentBackgroundColor)
_submitButton.setStyle('backgroundColor', currentBackgroundColor);

Stray references will prevent gc
Stray references will prevent gc
Event listeners are the single biggest cause of stray references
Weak References vs removeEventListener

Understand how bindings really work
Understand how bindings really work
Binding to functions
Triggering bindings with events

Don’t ignore the warnings in FB Problems panel
Don’t ignore the warnings in FB Problems panel
Strive to have 0 warnings and 0 errors at all times

Don’t be a moron.
Don’t be a moron.
Don’t use Application.application
FlexGlobals.topLevelApplicaton is just as bad

Strive to make better mistakes
Strive to make better mistakes
Steer clear of the races
Be nice to your run time
Watch the leaks
Listen to the warnings
Don’t be a moron

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