Question

I’m making a rather large flash project and so I’m concerned about memory usage. At the end of each section of the application I remove the overarching parent element that holds the content. Although this remove the parent, does this also free up the memory for each of the children contained within this, or should I run an iteration to remove those prior to removing the parent?

I’ll give a little more explanation in-case I’m not expressing what I want:

addChild(movie1);
movie1.addChild(movie2);
movie1.addChild(movie3);

By using this code:

removeChild(movie1);

Does it remove movie2 and movie3 from memory or are they still stored, just unlinked?

Answer 1

Well, nothing is removed from memory so far , it really depends on how movie1 is referenced. Let’s say that later in the application you want to add movie1 again, you should find that movie1 is not only still here but it also contains movie2 & movie3.

var movie1:MovieClip;

whatever();
anotherMethod();

function whatever():void
{
    movie1 = new MovieClip();
    var movie2:MovieClip = new MovieClip();
    var movie3:MovieClip = new MovieClip();
    movie1.addChild(movie2);
    movie1.addChild(movie3);
    addChild(movie1);

    whateverElse();
}

function whateverElse():void
{ 
    //here, nothing is garbage collected, movie1 exists outside
    //the scope of this function
    removeChild(movie1);

    //now you can
    tryThis();

    //but if you do this you're effectively killing movie2 & movie3 , since
    //they're not referenced anywhere else.
    removeChild(movie1);
    movie1 = null;

    //this is going to throw an error , movie1's gone!
    tryThis();
}

function tryThis():void
{
    //yes ,it's still here with all its content
    addChild(movie1);
}

function anotherMethod():void
{
    var movieN:MovieClip = new MovieClip();
    var movie2:MovieClip = new MovieClip();
    var movie3:MovieClip = new MovieClip();
    movieN.addChild(movie2);
    movieN.addChild(movie3);

    // do all you need to do... 
    // then
    removeChild( movieN);
    getOut();
}

function getOut():void
{
   //life goes on without movieN, movie2 & movie3
   //waiting to be garbage collected
}