flow of control for sequential data processing
flow of control for sequential data processing
- Subject: flow of control for sequential data processing
- From: Daniel Child <email@hidden>
- Date: Mon, 18 Feb 2008 14:01:14 -0500
A while ago, with much help from the community, I set up a test app
with a central controller and various peripheral window controllers.
The central controller kept references to the other window
controllers, and loaded each only when needed. The window controllers
could in turn communicate back to the central controller using the
fact that it was the NSApp's delegate. That worked fine for that
particular application since the flow of work logically centered
around a central location.
But now I have a different scenario.
I want the user to perform a series of tasks on some data in a
particular order, and each task has associated with it a controller
and a model to handle the persistent data. Something like:
[Controller A / Model A / perform step 1 tasks] followed by
[Controller B / Model B / use results of step 1 to perform step 2
tasks] followed by
[Controller C / Model C / use results of step 2 to perform step 3
tasks] etc.
where each controller is associated with its own interface and with a
certain data model layer. The data is being processed in each step,
and is then passed along to the next step for further processing.
Thus, for instance, once you have done the first step, there is no
reason to return to the interface provided by Controller A.
In each controller, I have been setting up references to the
controller used in the following stage, and then sending data long
with it. But I think this is going to be a problem in terms of
memory. If Controller A has an instance variable of type Controller
B, then if you "load" Controller B for it to do stuff, that loading
is done from within the context of A. How do you release A? If you
load B from A (B being an instance variable of A), then releasing A
is problematic because you are within the context of A.
I feel I'm stuck with a choice between a continual memory buildup or
circular references. And the way I keep passing bits of the model
around from one controlller to the next makes me think that the
design is flawed....something monstrous dish that resembles a cross
between lasagna and spaghetti.
Is there a better way to handle this kind of sequential data
processing from a design standpoint? Thanks.
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