Re: A tree data structure?
Re: A tree data structure?
- Subject: Re: A tree data structure?
- From: Jeffrey Oleander <email@hidden>
- Date: Tue, 5 May 2009 12:09:49 -0700 (PDT)
> On Tue, 2009/05/05, WT <email@hidden> wrote:
> From: WT <email@hidden>
> Subject: Re: A tree data structure?
> To: "Cocoa-Dev List" <email@hidden>
> Date: Tuesday, 2009 May 5, 12:19
> Please let's not forget that a tree data structure
> is often pretty much useless without some form of
> balancing...
The OP's post reminds me of a couple of mine back
around 2001, asking for threaded trees and
graphs and linked lists and such (with bi-
directional links and built-in support for other
threadng schemes).
You can always whip up a quick index into the
more complex data forest, as you build the trees
or after, if walking the structure isn't fast
enough.
I'm more concerned about how to manage what owns
the tree or forest (and the index), so that it
stays around and is accessible as long as
necessary, but no longer. I understand that
setters can do an autorelease and then the
caller do a retain as one way to pass ownership
up the line.
I might have a user who opens several files,
the data gets imported, converted, reorganized,
and then added to a model tree. The user is
likely to attach trees at particular node(s),
display these trees in various ways in multiple
windows and save the model tree in my native
format (or an export file format), most likely
after doing some editing in my editing interface(s)
to the model data. Maybe he opens or imports
various trees along the way, does some work,
sometimes saves changes, and closes some of
the trees, or just releases the file and the
associated NSData object once I've got the
data in model form.
What I don't get is how the life-cycle of
whatever object(s) own the tree, and of the
tree itself, fit into the application's execution
and event cycles. Sure, we've got model, controller
and view/interface. And we automagically have a
couple threads going. And the tree should be part
of/owned by the model, fed back and/or forth
through the controller to/from the interface(s),
but just at the moment, I'm missing some glue or
fasteners somewhere.
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