Problem when using function in function as timer event handler
Problem
Changing properties of display object isn't always successful in the timer event handler when the handler is a function in function
Solution
When trying to acess properties of display object within timer event handler, be careful not to use function in function as the handler
Detailed explanation
To implement a blinking effect of some button, one can use a timer with limited repeat count to flip the visible property in the timer event and set back visible when timer complete, as follows:
import flash.utils.Timer;
import flash.events.TimerEvent;
function doBLinkingButton():void
{
function handleTimer(e:TimerEvent):void
{
myButton.visible = !myButton.visible;
}
function handleCompleteTimer(e:TimerEvent):void
{
myButton.visible = true;
}
// repeat timer 6 times with 0.5-second cycle
Timer tmr:Timer = new Timer(500, 6);
tmr.addEventListener(TimerEvent.TIMER, handleTimer);
tmr.addEventListener(TimerEvent.TIMER_COMPLETE,
handleCompleteTimer);
}
Looking good, right?
If you run this code, you'll find for even-number times the handler executes, the flipping of visible properties won't succeed! The reason is because we are using a function in function as an event handler.
If you move handleTimer function outside doBLinkingButtion function to make it a class-level method, then the flipping will succeed each time handleTimer is called.
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