Actionscript 2.0 vs Object.addProperty()
Monday, 14 February 2005Over the past 6 months or so I have been utterly consumed by the task of designing and building our content management system. The administration interface is written entirely in Actionscript 2.0, and I have learned to love that language like a brother* - I don't think I'll ever touch a line of Actionscript 1 again if I can help it.
In the administration application, we have a data class that represents a page that has an extensible collection of 'properties' (as we call them in the system - sorry about the confusing nomenclature) along with methods to allow properties to be added. The class also has a number of regular private properties, along with Actionscript 2.0 style getter / setter methods for those properties.
A super-simplified version of this class might look something like this:
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class Page {
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private var __properties:Array;
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private var __title:String;
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private var __path:String;
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public function get title():String { return __title; }
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public function get path():String { return __path; }
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public function Page(Void) {
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__properties = new Array();
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}
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public function addProperty(prop:Property) : Void {
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__properties.push(prop);
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}
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}
While the above may look fine (especially if you only code in AS2), you'll find that the getter / setter methods don't actually work on objects of that class.
Half a day and several strong cups of tea later, I finally remembered that the underlying Object class has a method called addProperty(), and that method is what you use to register getter / setter functions for an object in AS1. Actionscript 2.0 classes compile down to the same byte-code instructions as AS1, so your getter / setter functions actually end up as __get_PROPERTY() and __set_PROPERTY() and uses Object.addProperty() to register them against PROPERTY in your class objects.
So, because I has implemented a method called addProperty() in my own class, and because all classes are ancestors of Object, I was hiding the Object.addProperty() method, which meant that the getter /setters were never registered.
Having worked exclusively with Actionscript 2.0 for so long, it took me a good half day to figure out why this was happening. I just wanted to post this up here as a reminder so that others don't make the same mistake! It's certainly an easy mistake to make now that we have a proper syntax for getter/setter methods instead of having to register them ourselves. Certainly a compiler warning would have been nice!
* A really good brother would have given me proper private members instead of the pseudo 'protected' members that we have now, but that's another post for another day.
--Update--
Typical! Having just added syntax highlighting to this blog, I can see that the addProperty() method is now highlighted as a keyword. If I'd used an editor that did this in the first place, maybe I could have saved myself from this whole sorry debacle. Sadly there's a distinct lack of good Actionscript 2.0 editors for OS X, basically it's TextWrangler or bust!
You should try TextMate. I have been playing with
Will | Wednesday, 16 February 2005 | 1:21 amYou should try TextMate. I have been playing with a command that will send my AS project to mtasc for compilation, send errors as HTML to TextMate and then show the updated file. I can do all this without launching the Flash IDE.
Will: I keep giving TextMate a try every time they
Steve | Wednesday, 16 February 2005 | 11:33 amWill: I keep giving TextMate a try every time they release a new version, and I absolutely love its project folder view and code collapsing, but I’m currently lumbered with an old 733MHz G4 (until next week when I get a shiny top of the range G5 - woohoo) and it’s seriously sluggish when trying to scroll around a large .as file.
Steve: Really, I would not imagine that it would
Will | Friday, 18 February 2005 | 12:06 amSteve: Really, I would not imagine that it would be so sluggish. Did you email the author about this? I ran it on my G4 1.25 Powerbook, 1.67 Powerbook and G5, they all behave about the same as far as scrolling. How many lines does your file have?
Steve: Can you shoot me an email. I
Will | Friday, 18 February 2005 | 12:07 amSteve: Can you shoot me an email. I could not find your contact info anywhere!
Will: Email Sent. I didn't email the author, as I
Steve | Friday, 18 February 2005 | 10:22 amWill: Email Sent. I didn’t email the author, as I just assumed that my ageing G4 was past it - there’s a heck of a lot of difference in processing power (almost double, not to mention bus speed improvements in later G4s) between a G4 1.25GHz PowerBook and my G4 722MHz PowerPC. I have problems with files that have ~700+ lines of code.
hi steve, is it possible to take a look at
jeremy | Wednesday, 02 March 2005 | 1:12 amhi steve, is it possible to take a look at your flash-based CMS ? or online-demos ?
thanks
Steve I know this is probably the wrong place, but
Tim Thompson | Saturday, 19 March 2005 | 10:49 pmSteve I know this is probably the wrong place, but I want to learn about the Flash-Based forum that you created. and possibly get the soure so I can create one of my own, for an existing project. Please email me asap maddogg54@comcast.net