Creating you own class

Question

Iv'e created an empty movieclip in my main fla. and assigned
it's AS 2.0 Class to a custom class i created in an external as
file.
I want my custom class at some stage to draw an
emptyMovieClip into this containing movieClip on the main fla.
I tried using, in the class draw procedure:
this.createEmptyMovieClip(all the gubbins in here);
But it doesnt work, i tried changing the "this" for "_root"
and this works but i'm not sure where its drawing the movieClip
too, surely that would be drawing it onto the root stage and not
into the movieClip container.
Another methods i did to get around this was in the draw
method of the class pass in a movieClip target i.e. would use:
containerMC.drawChart(containerMC);
This works fine but it seems a little stupid to me, is there
not some way to reference the containerMC in the class definition
(given containerMC wont be a constant name, i.e. depends on
instance name).
Anyway hope that makes sense, thanks for any help you can
offer.

Answer 1

Tolk,
>> Iv'e created an empty movieclip in my main fla. and
>> assigned it's AS 2.0 Class to a custom class i
created
>> in an external as file.
As Jensen mentioned, your class will have to extend
MovieClip for this
to work.
class MyCustomClass extends MovieClip {
If you don't do that, your class is just a class; in other
words, it just
instantiates an object (whatever object you define in that
class). If it
extends MovieClip, then it *is* a movie clip -- plus whatever
else you
define.
>> I want my custom class at some stage to draw an
>> emptyMovieClip into this containing movieClip on
>> the main fla. I tried using, in the class draw
procedure:
>>
>> this.createEmptyMovieClip(all the gubbins in here);
That would only work if the "this" reference resolves to a
movie clip.
Since your class doesn't extend MovieClip, none of the
MovieClip features
are available to it, including createEmptyMovieClip(). If you
don't extend,
you'll have to use composition here -- meaning, declare a
MovieClip property
in your class and use *that* as your movie clip reference.
>> i tried changing the "this" for "_root" and this
works
Sure thing. _root always points to the main timeline of the
currently
active level. The main timeline is, effectively, a movie
clip.
>> but i'm not sure where its drawing the movieClip
>> too, surely that would be drawing it onto the root
>> stage and not into the movieClip container.
Bingo.
>> Another methods i did to get around this was in the
>> draw method of the class pass in a movieClip
>> target i.e. would use:
>>
>> containerMC.drawChart(containerMC);
That's a thought, sure. Otherwise, how would an instance of
your class
know where this container clip was? Attaching it to the movie
clip isn't
enough. Seems like it should be -- I can see that -- but that
attachment
business is only for classes that extend MovieClip (as far as
I know).
David
stiller (at) quip (dot) net
Dev essays:
http://www.quip.net/blog/
"Luck is the residue of good design."