When overriding “commitProperties” put “super.commitProperties” call to the end of the method

February 3rd, 2010

My use-case
   Recently I’ve tried to introduce skin states to the pretty complex UI component in Adobe Flex 4. I have got puzzled by the behaviour that my invalidateSkinState() calls never had triggered execution of getCurrentSkinState method that controlls the current UI component skin state value as expected.

[pullquote]Invalidation of the same phase while processing that phase is ignored – by Alex Harui[/pullquote]

   Under closer examination I found out that I fall into the same invalidation trap that James Polanco did in November 2010.

   I must stress out that it was easy to fall into this trap in my case because inside “commitProperties” call I was doing pretty complex calculations that involved, for example, the creation of display object sub-children, listening for “preinitialize” events from those sub-children, reacting to it, etc.

    To cut the talk short, to prevent this property invalidation trap from happening I suggest to always follow the simple rule of the thumb:

When overriding “commitProperties” put “super.commitProperties” call to the end of the method

override protected function commitProperties():void
    if (myPropertyChanged)
        disableMyUIComponent = true;
        myPropertyChanged = false;
override protected function getCurrentSkinState():String { 
    var returnState:String = "normal"; 
    // Use information in the class to determine the new view state of the skin class. 
    if (disableMyUIComponent)     { 
        returnState = "disabled"; 
    return returnState; 

Futher reading:
Discussion at 2008 at Flexcoders mailing list (yeah, at that time, this mailing list was more interesting to read) “Must call super.commitProperties at END of overrided commitProperties when extending XXXX?”