What happens to dynamically declared variables when I'm not using them?

Question

Hello, I'm making a game using Flash Pro cc. But I wonder what happens to aTile, which is dynamically declared MovieClip variable through a loop. And each aTile gets the 2 EventListener's.
for(var i:Number=0; i<pVector.length;i++){
    var aTile:ATile=new ATile();
    aTile.x=pVector[i].x;
    aTile.y=pVector[i].y;
    aTile.gotoAndStop(Math.ceil(Math.random()*Color));
    nVector.push(aTile);
    Spr.addChild(aTile);
    aTile.addEventListener(MouseEvent.CLICK,Clicked,false,0,true);
    aTile.addEventListener(Event.COMPLETE, stop,false,0,true);
     // the current function ends here. what happens to aTile now ?? Is it going to be garbage collected? By the way, this piece of code runs whenever a player starts a new level of my game. And I don't make use of the aTile variable in other functions. I use only the nVector variable. And does declaring a dynamic variable in a loop mean a multiple of them are created? For example, if I loop the piece of code above 5 times, does it mean 5 aTile variables are created? Or each time you declare
var aTile:ATile=new ATile(); again, does it replace the 'old' aTile with the 'new' aTile and therefore only 1 aTile exists after the loop????

Answer 1

I feel there is a gap in understanding of using variables by reference vs. by value. You should look it up.
1. new instructs Flash to create a distinct instance that per se has absolutely nothing to do with aTile variable.
2. REFERENCE to this new instance is assigned to variable aTile. aTile var is a temporary pointer to instance.
3. It does not replace old tile - it replaces reference.
4. If reference to the instance is not stored elsewhere - upon exiting of function this instance will be gced.
5. By creating another reference to the instance you prevent it from GC. One of the ways you preserve instance is by adding it to display list when using addChild.
You can look at this this way (it is a lame example but still it illustrates parts of the concept)
Say you have
1. basket;
2. basket is small and can hold only one apple;
3. table;
4. an apple;
5. apple can be placed into the basket or table;
6. dog who love apples.
7. Dog is trained not to take apples from baskets but table but is free to eat apples that are on the ground.
So, once apple is in the basket or on the table - it is safe.
If you move these entities into the realm of AS3, basket and table become declared variables, apple an instance and dog garbage collector.
What this example demonstrates is that apple exists independently of basket or table. You can put apple to the basket OR on the table OR you can put apple into basket and place basket onto the table.
1. Find apple instance (if you know whether apple is in the basket, on the table or in the basket on the table)
2. Prevent dog from eating apple.
3. Allow dog to eat it (destroy it when garbage collector kicks in) by assuring that apple is in neither basket or on the table.