[Laszlo-dev] Flash built-in objects

[André Bargull]

I've tripped over that 'feature' while updating the music example 
application to show some ID3 infos.
First I've tested "if (id3 != null)", that worked perfectly under swf9, 
but it was ´false´ under swf8. Let's say, I was a bit stumped at that 
time. Then I tested all these variations to find out what is so magic 
about the id3-object in swf8. At least "if (!! id3)" works in both 
runtimes. :-)

On 9/16/2008 4:54 PM, P T Withington wrote:
> Flash is not very good about their built-in objects behaving as objects.
> 
> Adam used to use something like this to test for an object being a 
> function:
> 
>   if (x == null && (! x)) ...
> 
> So, functions are similar to null and false in a boolean context, so 
> this might be part of that old hack?
> 
> On 2008-09-16, at 10:38EDT, André Bargull wrote:
> 
>> Some Flash8 built-in objects are too scary:
>>
>> var id3 = audioplayer.getID3(); //audioplayer is a LzView
>> typeof id3; // 'object'
>> typeof id3.constructor; // 'undefined' -> aha, a built-in object
>> id3 == null; // true
>> id3 == undefined; // true
>> id3 != null; // false
>> id3 != undefined; // false
>> id3 === null; // false
>> id3 === undefined; // false
>> id3 !== null; // true
>> id3 !== undefined; // true
>> Finally:  !!(audioplayer.getID3()); // true
>>
>> Whatever their indention was....!?
> 
>