Storing a reference to parentObject in the dictionary simply moves
the problem. You still need to delete that last reference yourself.
Charles Yeomans
On Jan 5, 2007, at 9:23 PM, Tom Benson wrote:
Hmmm.. you could .hash all of your objects, and then have a
dictionary key(child.hash),value(parentObject)
that would break the cycle without too much overhead, enabling you
to have a reverse lookup table stored in a seperate module.
Everytime you instantiated a child you'd need to make an entry in
the dictionary though.
You could then traverse down the tree with parent.child, but to
traverse up you'd need to do parent = child.lookupParent(child.hash)
On 06/01/2007, at 11:02 AM, Frank Condello wrote:
On 5-Jan-07, at 5:56 PM, Stefan wrote:
Am 05.01.2007 um 23:43 schrieb Daniel Stenning:
Seem to remember someone mentioning that monkeybread supporting
weak
references in their plugin collection, not ideal I know, so I'll
sign on to
that F.R in any case.
Some time ago, we had a lengthy discussion regarding this.
I personally had a problem based on cyclic object graphs. As far as
I remember, RS explained, that cyclic object graphs can always be
rewritten to acyclic graphs. Furthermore, I remember that someone of
RS explained, that cyclic graphs are often a sign of bad design
[which
I can't confirm].
I don't know - cyclic references are really useful for tree
structures where you need to traverse the tree backwards. E.g. in
my 3D scene graph nodes can contain child nodes, and each node's
transformations (position/orientation/scale) affect its children.
The renderer traverses the tree from the root so children needn't
know about their parents in that case. However, nodes must have
knowledge about their parents to glean data such as their absolute
world coordinates. I could traverse the whole tree from the root
until I find the node I'm interested in but that's a huge waste of
time - it's far easier and faster to traverse the tree backwards
until you hit the root.
So for right now I use cyclic refs and require nodes to be
disposed of implicitly, giving them a chance tell their children
to trash the parent ref. To ensure I haven't missed any I check
the Runtime module for dangling nodes in the App.Close event. This
works OK, but is quite the PITA, so if anyone's got a reasonable
acyclic solution I'm all ears...
Thus, I really wonder, if RS would implement this feature request.
Well I hope they seriously consider it - the scene graph aside, my
current file caching scheme is a complicated mess that would be
greatly simplified and require far less code with weak refs...
Frank.
<http://developer.chaoticbox.com/>
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