Instantiate an AS2 class which is a MovieClip?

Question

I have a simple class which extends MovieClip and requires
one constructor argument, we'll call Box. This class is associated
to a MovieClip in the library. I can't for the life of me figure
out how to actually instantiate it at runtime:
new Box('hello world'); // doesn't work, the MovieClip is
never attached on stage
attachMovie('Box',getNextHighestDepth()); // attaches, but
doesn't pass constructor argument
How should this be done?

Answer 1

When you extend MovieClip you either instantiate an instance
by placing the associated movieclip from the library on the stage
or by using MovieClip.attachMovie() or
MovieClip.duplicateMovieClip();
Using a constructor - as you have noticed - doesn't work in
this scenario. The class can have a constructor (but it is not
adviced) but you cannot pass any arguments.
One way to solve this is by passing arguments in the
initObject parameter of MovieClip.attachMovie().
this.attachMovie("myMovieClip","example",10,{txt:"hello
world"}); //linkage identifier set to 'myMovieClip'
or with
this.attachMovie("myMovieClip","example",10);
example.txt="hello world";