Looking for a practical reparenting example.

Question

Hello,
I have noticed a number of CS3 + /AS3 books mention how much
easier reparenting is now in AS3. (which may be true). What I am
struggling with is why anyone would reparent something in the first
place. Any practical examples of why someone would do this and why
it would be a prefered method would be greatly appreciated.
Thanks,

Answer 1

MATTANDIE,
> I have noticed a number of CS3 + /AS3 books mention
> how much easier reparenting is now in AS3.
It's not that AS3 makes it easier; it's that AS3 makes it
possible.
> What I am struggling with is why anyone would reparent
> something in the first place.
The example I tend to use -- only because I think it's the
easiest to
grasp, for programmers and nonprogrammers alike -- is a
jigsaw puzzle
application. Imagine a jigsaw puzzle done in Flash, in which
you drag
pieces around in order to construct an image (just like real
life).
Generally, this sort of thing is done with movie clips. The
easiest
approach is to use the native MovieClip startDrag() and
stopDrag() methods.
It can be a nice feature for snapped-together pieces to move
as a single
group. Doing so in AS2 means looping through those
snapped-together pieces
(keeping track of adding them, removing them, etc.) and
moving them all when
any *any one of them* is dragged.
Doing so in AS3 potentially means removing them from their
current
parent (say, the main timeline) and adding them to a new
parent (a container
just for snapped-together pieces). To move the whole group,
all you have to
do is apply a drag/drop routine to that one object.
> Any practical examples of why someone would do this and
> why it would be a prefered method would be greatly
appreciated.
I can think of other example, off the top of my head. You
might be
coding up a game in which numerous enemies are chasing the
hero. By
reparenting those enemies into a single group, you can run a
hittest against
the combined object to discern when the hero is coming too
near *any* of
them. When that happens, you could then determine which enemy
is the
closest, and remove that one entity from the group,
reparenting it to the
same timeline as the hero. In this way, you could focus your
hittest
routine on as few objects as possible, whereas in AS2 you
might have had all
your enemies "loose" in the same timeline as the hero. Your
hittests might
either be lesser optimised (always looping among all enemies)
or less
accurate (all in one group) -- but couldn't enjoy the best of
both worlds.
Does that help?
David Stiller
Adobe Community Expert
Dev blog,
http://www.quip.net/blog/
"Luck is the residue of good design."